Episode 175

We’ve discussed sleep and its impact on cognitive function before.  We’ve also talked about various ways to optimize your sleep.

One common recommendation when it comes to improving sleep is to avoid bright light, particularly blue light, at night.  But you can actually use light to your advantage in sleeping better.

Dr. Scott Killgore, Associate Professor of Psychology at Harvard Medical School, and Timo Ahopelto, the Finnish serial investor behind the HumanCharger and the Ōura ring, join Jesse on this episode to discuss sleep and light therapy.

Sleep Deprivation is Bad, Very Bad

Do you really need to hear this again?  Sleep deprivation sucks for your brain.  It affects your mood, your morality, your cognition, and your likelihood of making risky decisions.

You’ll also see a decline in emotional intelligence.  There’s a significant decline in your overall ability to use emotions during periods of sleep deprivation.  You become more emotionally volatile, with a lower tolerance for frustration.

In more bad news, you don’t actually recognize your deterioration.  In multiple studies, participants’ sense of sleepiness will plateau at a certain point of sleep deprivation, but their performance will continue to decline.

Sleep Deprivation Resistance

One area of our cognition that seems resistant to sleep deprivation is higher order cognition, including the ability to plan.  It’s fairly resistant to sleep loss and we don’t see massive declines.

Interestingly, introverts are better able to resist sleep deprivation.  According to Hans Eysenck’s theory of personality, introverts have a higher base level of cortical arousal than extroverts, that’s why they don’t need additional outside stimulation.

Introverts are better able to sustain performance after one night of sleep deprivation.  However, their advantage over extroverts fades after subsequent nights of lack of sleep.

Finally, while healthy normal individuals see an increase in depression and anxiety while suffering from sleep deprivation, clinically depressed individuals experience the opposite.  They become less depressed when sleep deprived, although the research isn’t clear as to why.

The Connection Between Light and Sleep

Our circadian rhythm aligns with environmental levels of light.  Exposure to light suppresses melatonin production, which promotes sleep onset.

Exposure to light in the evening, especially blue light, emitted by electronics, disrupts this natural cycle.  And don’t think you can turn off your computer and try to fall asleep an hour later.  The negative effects last for several hours.

So we know about the detrimental effects of light, but we can harness light in a positive way.

One way is by getting more exposure to natural light — blue light — in the early morning.  Get outside, even if it’s overcast.  When you get early morning sunlight, you’ll feel more alert during the day and sleep better at night.

Benefits of Bright Light

Exposure to bright light at the right time of day has a whole host of further benefits.  During winter months, when there is less sunlight, many people experience lethargy or depression.  Finns know this more than most.

Ahopelto and his team found a surprising solution, and it’s as easy as sticking earbuds in your ears.  The HumanCharger looks like an iPod with earbuds, but instead of playing music, it shines bright light into your ears.

Just 12 minutes of this bright light in your ears is enough to get rid of “winter flu” symptoms.

And this is just the start of the possibilities of light therapy.

Dr. Killgore is currently conducting research on using light therapy to treat brain injuries.  The theory is that by getting better sleep, your brain will have a better chance at healing itself.

While the data is still preliminary, it is promising.  After six weeks of light therapy, quality of sleep has improved, and there are structural changes in the brain that are hopefully associated with physical recovery.


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Read Full Transcript

Dr.  Scott Killgore: So, I joined the Army and the first assignment that I got was in a sleep lab.  And I really didn't know anything about sleep but they had me working in a lab where they were doing experiments of total sleep deprivation.  They were keeping people up sometimes up to 88 hours with no sleep at all.

Jesse Lawler: What is the methodology for that, by the way?  I imagine medieval torture devices but it's probably something else.

Dr.  Killgore: It's actually fairly simple that we just had a room with research assistants that would stay there on a shift.  And so they would go for about eight hour shifts and they just keep watching the participant as they were in the room and they just never let them sleep.  If they start getting sleepy they have to stand up, walk around the room, keep watching some TV, play some games, get something to eat but they're not allowed to leave the room.  They're not allowed to exercise.  They just basically stay there and stay awake for two or three days at a time. 

Basically, they were doing studies looking at simple reaction time and what they call psychomotor vigilance - how well you can stay focused on on a very boring spot on a screen and respond every time that point changes in some way.  It really didn't go beyond that for a lot of the previous studies.  What I was most interested in was emotional processing and executive functions and these higher level cognitive abilities that people have and they had really not been explored at that time to see how sleep deprivation might affect those.  So we wanted to start taking a look at what happens to the brain and cognition when a person is sleep deprived, and how does that affect your higher level judgments, your decisions, your willingness to engage in risky behaviors and moral decision making processes.

Jesse: Eighty eight hours or up to 88 hours is a heck of a long time.  Was the degradation somewhat linear or what sort of variations were there?

Dr.  Killgore: Well, what we know in sleep deprivation is that your sleep pressure or the biological drive for sleep is overlaid on top of what's called your circadian rhythm of alertness.  So when you combine those together you get sort of this downward rhythmic pattern that gets worse and worse in a linear way but it increases or decreases throughout the day.  So at times when your circadian rhythm is actually on the upswing you may be very close to your normal level of performance, but over night when your circadian rhythm starts to drop again, you see this dramatic drop in your overall cognitive abilities.  But what we know about sleep deprivation is that your sense of sleepiness essentially plateaus at a certain point.  So you don't feel any more sleepy after about one night of sleep deprivation. 

Jesse: That's interesting. 

Dr.  Killgore: Yeah.  You continue to get worse which is what's the scary part about it is your performance continues to degrade, but you don't feel any sleepier.  And so your judgment changes.  You don't know that you're in such an impaired situation.  You go for two days without sleep.  You're a lot worse than you were at one day without sleep but you feel about the same.  And so you don't know that you're getting worse and that you're at a higher risk of having a car accident or making some kind of mistake.

Timo Ahopelto: Originally, this was an intervention by two senior scientists.  The other one of is more an engineer and the other one was more in the physiology.  On the animal side, studying pigeons, birds, and even fish.  It's a well-known fact that you actually don't need to have light into your eyes to have the typical refreshing effect that life has.  It's enough to get it somewhere in your body or to the area off your head.  This was kind of a pondering question in a way.  I mean could this work in humans?

I mean people have been out there in the circuit and rhythm of birds by projecting light into their head instead of projecting light into their eyes only.  That's a very well-known phenomenon in animals in zoology.  Nobody has tested that to humans.  Then, there was one Nokia engineer in Oulu which is very north in Finland.  I mean the sun never gets up there during the wintertime so it's very dark and I mean he was totally depressed during the winter time.  He contacted the other guy and said that “Hey, you know now this is enough so I'm going to illuminate my whole house with bright lights and it's going to be very expensive and it's going to be a big project.” The other guy said “Hey, don't do it.  Let's try to illuminate your head and let’s see what happens.”

The Nokia engineer thought that hey you know people are so used to wearing all sorts of earplugs listening to music and having podcasts on everything but maybe what if we project light via ear canal inside of the head.  The physiology guy said that “Hey, that's great news because basically your ear canal is like a direct hole inside of your head or into your head.” Then they started testing and they realized being refreshed themselves.  They did a couple of more devices, and this is 2007 to 2008.  They gave them to their friends, and the friends more energized during this north and the very dark winter.  Then they started to do more like a cointreau test and a clinical trial, and figure it out that there must be something in base.

And then of course packaging it into iPod like device.  I mean iPod was very big at that time when they put together the first device.  They’ve kind of seemed pretty obvious in a way.  And of course it's condering to dim light.  You should be listening to light while you canal--.  So that was the starting point, and then it was an immediate aha moment kind of a thing in a way that this is so counterintuitive and at the same time scientifically, and then I'm thinking about what has been learned about the animal physiology.

It's so natural and there needs to be something and that was the starting point. 

Jesse: Looking at the effects of sleep deprivation on cognition, what did you find about how that hurts us.  I imagine that there's lots of detrimental effects but it might be different maybe in some types of brain activities than others.

Dr.  Killgore: The ones we were most interested in had to do more with the emotional side of things.  What we found was that when people are deprived of sleep which is no big surprise in a sense but people's ability to use their emotions to make good decisions actually starts to become impaired.  So they show a decrease on standard measures of emotional intelligence.  So we actually had an IQ test that our subjects had to take before they were sleep deprived. 

And then when they were sleep deprived we found that there was a significant decline in their overall ability to use their emotions effectively and a decline in their overall empathy for other people.  We actually gave them a very interesting task that isn't used much anymore but it was like a cartoon task where we had them look at cartoons that had empty bubbles above the heads and they had to fill in what they thought the person in that situation would say.  It was a frustrating situation.  Like the person lost the car keys and the wife is standing there and she's got a bubble above her head says it's a fine time to have lost the car keys and then you have an empty bubble for the husband.  And you have to write in what his response will be.  Basically, what we found was that in that kind of situation, people had much lower frustration tolerance and they tended to blame the other person for the situations much more.  They didn't do well emotionally in those kinds of situations.  They really took the blame off of themselves.  It was always the other person's fault.

Jesse: Were there any aspects of cognition that weren't that adversely affected by sleep deprivation that did surprisingly well.

Dr.  Killgore: Well, what's interesting is the area that we were most interested in is higher order cognition like executive functions, the ability to plan and sequence and think several steps into the future.  Sometimes we thought for sure that those would show severe deficits.  Amazingly oftentimes they were quite resistant to sleep loss.  So you go for a couple of days with no sleep.  We thought for sure people would have a hard time planning out several steps into the future or making good decisions in some ways.  And in fact they did just fine on those kinds of executive function tasks which was not what we expected but people could do it and some of the theories behind that is that these kinds of tasks are very interesting.  It's fun to solve a problem. 

If you've been sitting in a sleep lab for the last two days being very bored it's actually kind of exciting to sit down and take Wisconsin card sorting test or something else that stimulates you a little bit and that stimulation itself may actually be enough to help you to perform well or do better than you would have otherwise.  But it's short lived.  It's only for just five minutes or so that you can focus and do okay on those kinds of tests.  But when it's a boring task like a psychomotor vigilance task which last for 10 minutes those things are very boring and it's really hard to stay focused on those.

Jesse: I saw that some of your studies dealt with introverts and extroverts and the sleep deprivation actually affects those demographics differently.  That's sort of counterintuitive.  I was wondering (A) Can you tell us about that?  And (B) What led you to even think in that direction?

Dr.  Killgore: What we're talking about really is individual differences in the ability to resist sleep deprivation.  Interestingly about 12, 13 years ago there were a number of studies that came out starting to show that people differ in their ability to stay up all night.  Some of us just don't need much sleep and we can function fine even with a day or two without sleep.  And we don't show a lot of deficits.  Others are very impaired and they show very severe deficits when they stay up all night.  And what's interesting is it's a very consistent trait like phenomenon.  So within the same individual each time that you sleep deprived that person, you get a very similar response.  Even if I were to sleep deprive you in February and then bring you back in March and sleep deprive you again, if you were resistant, you would be resistant both times.  So it's a treat like phenomenon.  So we get to thinking maybe there are some others stable treat like things that might predict that and so a lot of investigators have tried to identify are there biomarkers?  Are there things in your blood?  Are there genetic components?  Are there differences in brain shape or brain size or brain function? 

An obvious one was to look at personality differences.  Maybe some people differ in the personality traits that help them to stay awake more.  The basic theory that we had was based on Hans Isaac’s theory of cortical arousal.  This is a theory that extends way back many decades in personality.  His basic theory was that introverts tend to have a higher level of basal arousal to begin with.  That's why they're introverts.  That's what they like to go to the library.  They prefer to be alone because their brain is already jacked up to begin with, they don't need more stimulation.  Whereas the extrovert is actually low in their basal arousal so they seek out external stimulation.  They need to be with other people.  They need to get around other stimulation to make them feel at their optimal level of functioning. 

So it seemed reasonable to think that if you were an extrovert, your basal level of arousal is low to begin with, maybe you might actually be more vulnerable to the effect of sleep loss because it will take less to drop you down to that level of falling asleep whereas the introvert is actually highly aroused.  It's going to take further for them to move down the graph and actually fall into that state of sleep.  So we tested that out and in fact that hypothesis was supported.  What we found was that introverts were better able at sustaining performance during the first night of sleep deprivation relative to extroverts.  It sort of falls apart after the second and third nights without sleep.  But the first night it seemed to hold up fairly strongly.  Then we also followed it up with a second study where we're interested in whether introverts and extroverts would differ based on social enrichment or not.

In other words we gave them a party in the lab.  So we brought in these introverts and these extroverts so we screened them very thoroughly to make sure they fell into one or the two camps and then half of the subjects got essentially what we called a party.  They had the research assistants engage in very social ways with them.  They played lots of games.  It was very festive, very active kind of an atmosphere where we did the same experiment where every subject went into their own isolated room and they never had contact outside of an intercom.  With the research assistants.  So no social interaction.  They did all the same tasks.  They played all the same games online but there was no human interaction involved in the situations.  And then we controlled further their overall level of activity with a risk work activity monitor to make sure that it wasn't just one group being more active than the other. 

What we found was that it was actually the extroverts that were most affected by the party in a negative way.  What we found is that the extroverts, it wore them out faster to be in that social situation when they were sleep deprived that when they stayed up the next night they dropped off much faster in their ability to sustain performance whereas the introverts were able to sustain throughout the night even though they'd been exposed to the party.  And that was opposite what I was initially expecting to have happen but it seemed to be a fairly robust phenomenon.  Our theory about it is that actually the extroverts were more engaged and were using their prefrontal cortex in those situations a lot more.

There's a whole theory of sleep deprivation that it's called kind of a used dependent decline in a sense where the more you use the area of the brain just like a muscle, the more tired it becomes and it starts to fall asleep easier as you go for a longer period without sleep.

Timo: If you look at the brain atlases which are out there, nobody had been studying the brain tissue on whether or not the brains are sensitive to light.  It just hasn't been in the research focus.  When these guys did it, they first started with the imaging studies.  So they put people into the dark room.  Eyes totally covered so that they couldn't see anything.  Then they put this stuff for light guides into their ears.  And then without the controlled version knowing they switched the lights on and off and then they did brain imaging at the same time, and they very well to show that certain brain areas actually get activated because of the light projected onto them after like three to six minutes of exposure.  That was the big revelation in a way that hey, the light actually penetrates the brain and it actually has an effect in the human brain.

So something's happening and of course the fact that something is happening doesn't mean that something is happening therapeutically but it has some effect.  If you scratch your skin, I mean something happens but it doesn't make you feel any better, right.  So that was the starting point. 

And then they started to figure out that you know why is this happening?  What is there in the brain that is sensitive to light?  They actually got a very rare sample of brain tissue from cadavers that.  It's very rare to get that.  The amount like roughly like a 10 total brains that you're going to study.  They did brain staining and I found that actually the human brain is full of proteins called opsins especially opium 3 and opium 4 which are fully sensitive to light.  So they belong to the same family of proteins that you have in your eyes, in your retina to detect light.  That was the kind of idea that hey, if these brain areas are actually covered by this light sensitive protein matter, there needs to be a function with them.  If they weren’t in evolution, those proteins have stopped to exist in a brain but digging deeper into the literature you're going to actually find some early studies where some medical technology company, some scientists groups have been studying that how does the light penetrate into the brain?  They are concluding that the skull is actually letting a lot of light inside of your head during a sunny day.  So it's actually a surprising amount of tight that’s penetrating to the skull.

Jesse: Wow that's surprising.

Timo: Yeah that's right.  And in living here in the northern latitudes the next step was then to start figuring out that does this really make people feel better during winter time?  And there's a term for this it's called seasonal affective disorder or winter flues in the milder form in the very northern latitudes like one or two out of 10 people suffer from winter flues.  Even in New York latitudes, it's like one out of 10.  People just don't realize that they have it.  It's like a downward mood during the winter months.

These studies were conducted with really depressed people to see if there’s efficacy.  It was surprising to see that in the first studies there were of course golden label trials like you typically start to develop and these other things.  Between 80 to 90 percent of people who participated basically got rid of all the winter flues symptoms during a period of four to eight weeks of treatment.  The treatment is daily 12 minutes of light.  So you push one part and it gives you a 12-minute light dose.

Jesse: How did you zero in on the 12 minute figure?  Is that equivalent to 12 minutes of bright sunlight or is this such concentrated light that it's giving you more than one minute per minute versus what you get from the sun?

Timo: It's a really interesting question because if you would be developing groks, you have this dose escalation trials where you're trying to figure out what is the right amount, or if you have 10 milligrams of ibuprofen it doesn't make your headache.  But if you have a thousand milligrams it's probably two months, three to four hundred is probably enough so you have to kind of titrate the right dose. 

Then here was the scientists in the university were able to see that the brain networks actually get activated after a three to six minutes of light exposure.  Then in some of these like early tests that were done in the university, it seemed in a way that the dosing amount between 6 to 12 minutes is the right amount.  And that's why it's always a combination of art and science.  What is the right dosing when you're going to this sort of scientific experiments and that's why the group selected 12 minutes and that's where all the studies have been done?

But if you look at the ear canal, or you would put anything into your ears you could realize that there's actually not too much brain between where your ear canal stops on the either side.  If you then look at what other areas attached are located in that area.  There's for example a three part brain area called raphae nuclei which is responsible partially for serotonin production.  There's the substantia nigra which is known to be for dopamine production.  They're obviously the hypothalamus which is hormonal control functions.  There are still all the melatonin production functions are actually almost directly where your ear kind of stops.

Those are the oldest brain areas if you believe that the brain has developed evolutionary in a way that you have it depending on who you listen to about two or three layers of the brain and obviously the cognitive functions are on the top and on your forehead.  But we have basic function and the hormonal function.  It is in the center of the old parts of the brain.  And there within few centimeters away from where the ear canal stops.  So the ear canal is the really effective way to put light into those areas.

Jesse: With the caveat that obviously you're the most biased person in the world to answer this question, but it seems like there's really almost no downsides to this technology.  You can't overdose on sunlight per se other than getting a sunburn.  If you spread it out to your ears for 24 minutes rather than 12 minutes, there's really no harm to be done, right?

Timo: Yeah.  I know that some people are using it for more than 12 minutes.  We cannot say that because we are operating under the medical device certificates.  So it means that we need to stick to what we have studied and we have studied in jet lag.  We have like a tree times 12 minutes a day and it is seasonal affective and winter flues and this energy increase we have a one times 12 minutes a day.  Some people who are like really sensitive to light, they have actually got back to us in a way that they can almost like the time by hour when they wake up compared to when they use the device so they basically say that “Hey, if I use the device like 8:00 p.m.  in the evening I would wake up at 6 a.m.  If I use it like 9:00 p.m., I would wake up at 7:00 a.m.  And so forth.

This affects the circadian rhythms and the cycles also.  Some people are light sensitive and timed into lights so in that sense you could also like mess up your circadian rhythm.  Probably easily if you would take the doses here and there.

Dr.  Killgore: In one of these studies, we gave them a measure called the personality assessment inventory or the PAI.  Essentially, it's a broad spectrum measure that looks at all different aspects of psychopathology and measures them on scales and then we were able to measure them again when they were sleep deprived and we found that there was an increase in levels of depression, levels of anxiety and somatic symptoms that these healthy normal individuals showed this dramatic increase in those levels of psychopathology. 

But what's fascinating about it is that if you're actually a depressed person, if you're suffering from clinical depression, we see the opposite pattern.  People who are depressed actually get feeling less depressed and may even get giddy at times when they're sleep deprived.  There's a lot of debate in the literature about that.  Why is it that depression seems to have this improvement in their mood when they're sleep deprived whereas healthy normals actually become more depressed when they're sleep deprived?  Nobody has really come up with a perfect theory on that yet.  We're playing with some ideas on how the prefrontal cortex may be involved in that but it's not ready for prime quite yet.

Jesse: There is that one thing that I think probably a lot of people will be familiar with when you stay up way too late you get kind of like a weird sense of humor.  It only seems to be there in that one particular state.  Me and my friends have called it Punchdrunk but I'm sure that's not the clinical term.  Do you have any insight on that?

Dr.  Killgore: I think it's related to the same kind of thing.  There were some studies that Matt Walker's group out in California has done where they've shown that when people are sleep deprived it alters the connectivity between the prefrontal cortex which is the regulating area of the brain that regulate your emotions and evaluates emotional stimuli.  And the more primitive areas like the amygdala that are involved in salience detection and emotional responses.  So you get sort of a dysregulation of the emotional systems in the brain and your ability to control and regulate those and what their studies seem to show is that it affects both positive and negative emotion.  It may come to do with whatever the stimuli are that you're being confronted with.  So if you're dealing with a sad picture or scary pictures those are going to affect you more and you're going to have some negative emotions.  But if it's actually funny and you're with your friends and you're seeing something enjoyable it may actually make you feel Punchdrunk and you're kind of giddy and having a good time with it.  It's the fact is you're not able to regulate your emotions the way you are well-rested.

Jesse: We talked about sleep hygiene in past episodes and ways to optimize a person's sleep.  Do you feel like there is particular approaches that the public is not clued in on enough things that science knows that the public might not about how to get sleep as optimized as possible.

Dr.  Killgore: I think the big one that we've been focusing in on is those circadian rhythms I was talking about before and aligning that with your light exposure.  A lot of people don't think about light and how light may actually be affecting their sleep.  And as I said before your homeostatic drive for sleep.  The longer you stay awake the stronger that drive is that's pushing you to fall asleep.  Just like when you haven't had water or food you have this drive to go eat or consume water.  The same thing happens with sleep but it's overlaid on that circadian rhythm.  And the big thing that affects your circadian rhythm is light.  There are other factors that play into it too but light is really probably the most powerful regulator of that.  I'm always surprised that people have not heard that much about it but that getting light in the evening is not usually a good thing especially blue wavelengths of light like what you get off your computer or your television screen or your iPad.  All of those things are emitting a blue wavelength of light.

What we know about light is that light suppresses the chemical called melatonin which is really what tells your brain that it's time to go to sleep.  So if in the evening time you're sitting here looking at the computer screen for several hours you're suppressing that chemical that normally is preparing the brain for a good night's sleep.  So it's going to shift you and tell your brain that instead of being 10:00 at night it's only seven o'clock at night.  So your brain is not ready to go to sleep yet and that can really impair your sleep.  So if there's one big advice I would give is to kind of turn off the smartphones and the computers earlier in the evening so that you're not being affected by that. 

And then on the flip side get more exposure to blue light in the morning hours.  For me, what I find is, I live in Arizona now and we got this beautiful sky in the morning.  So the first thing I do every morning is I get up and I go out and I have my coffee in the morning and I sit out for about half an hour and I just get that big blue sky out there and that radiant blue sky suppresses melatonin and sort of resets my circadian clock each day.  And since I've been doing that I've noticed that I sleep so much better at night when I get that early morning burst of blue light early on six to seven in the morning and I'm more alert during the day and sleep better at night.

Jesse: Now for those of us that don't necessarily have bright cloudless Arizona skies outside when we wake up in the morning, is blue light something that makes it through cloud cover or is it really one of these things that if you live in a - or in Seattle like environment you've got to take technology to the rescue.

Dr.  Killgore: No, no.  It's still enough that if you get outside that the amount of light that is coming through the clouds is white light.  So the amount of light that's coming through still has that blue wavelength embedded within it but white light has the entire spectrum.  So you're still getting the blue wavelength to suppress that melatonin So that's still a powerful effect.  May not be quite as much as a big bright blue sky but it's still a very powerful effect if you're out in it.  If you're sitting inside your living room and you don't have very big windows that dull gray is probably not enough to really be suppressing your melatonin at the level that you'd like but I would try to get outside if you can.  Even the morning drive is for a lot of people enough to start resetting that.

Jesse: How long does it take to shift your body into either melatonin production or melatonin suppression?  For example, let’s say you're doing everything wrong and you're in a bright lit environment until 9:00 at night but then 9:00 at night you go into your bedroom, it's dark, there's no light leakage, how long will it be until your body has completed that switch over into melatonin production?

Dr.  Killgore: It takes a little while.  When they do studies to look at melatonin, they usually have you sit in a room for several hours with a very dim amount of light so they call it a dim light melatonin onset and usually it's just within a matter of hours but it's following your circadian rhythm.  So you have a rhythm of melatonin that will come on naturally if you're not in bright light.  And so over the next hour or two your melatonin will start to emerge if you're in a darkened situation.  Just exposing yourself to some light can actually suppress it and shift it for up to an hour or so sometimes just by being exposed to even a brief pulse of light sometimes.

Jesse: So your team sent me a human charger which I've been using for a couple of months now.  Thank you very much.  And along with it a lot of the marketing materials deal heavily with jet lag and jet lag avoidance and shortening of jet lag after somebody has changed multiple times zones.  In this conversation, we've been talking about more mood and seasonal affective disorder, things like that.  Why is it that the product marketing seemed to emphasize so heavily the anti-jetlag effects?

Timo: We are projecting light into these photosensitive areas of the brain and on these photosensitive areas are activated by human charger.  What the activation means is we get these chemical compounds which are natural like serotonin, dopamine, and noradrenaline which are really -- that is kind of fleeting to increase energy levels, improving mood, mental alertness, and then again reducing the effects of jetlag.  Maybe the reason why there's so much of the jetlag is that -- we did a really trial in jet lag some time ago, one and a half, two years ago and we were so proud about it so we wanted to put it in front and in going that jet lag route it was pretty much like based on our own and our colleagues and our friend’s initial observation that when they were using this bright light therapy device while they were in a business travel or travelling for leisure they didn't have the jet lag.  So we did a study about it then the results turned out well.  So we are able to alleviate the jet lag symptoms.

Jesse: Do you have additional design iterations in the works for the human charger or is this a case where the technology is already doing what you intended and maybe meeting what you expect that science tells us is probably possible.

Timo: What we have right now working on is what we call human charger version three which would be like any headset that you pluck in your smartphone so we could have this podcast with that headset.  So it has voice integrated into it.  And are connected to the apps that were kind of automatically dosed the needed amount of light for you.  The problem with our modern lifestyles is basically that we are too much inside.  We are too little in sunlight.  We are too little outside.  In this type of a normal office lighting, it’s not really giving the necessary intensity level that you should have.  I mean if you have the whole of your day in an office, you are not really getting the light that you should be getting.  And that's a big problem. 

So what we did with humans charger, we have a test protocol where we kind of changed and altered this waveform or the spectral curve in a way that what is the right combination of the blue, red, and green light areas.  And then we have an idea about what type of spectral curves are stimulating which parts of the brain.  And that's what I think that if you would think about light 20 years ahead when everybody is using this as the natural therapy for even like a more severe case getting more energy which the current product is for.  The spectral curve might be totally different.  This is still under research area.  There are even light therapy device researchers who are well established, acknowledge.  And I really like a good research so I've been doing first the trial for example post-traumatic stress disorder which is cured with bright light very effectively.  They do one trial with the one set of bright light lamps and I mean the traditional light boxes.  They get tremendously good results.  Then they do the next study and they get a bright light manufacturer to sponsor it.  They get different results, and then again they're wondering about how this could be if I wasn't able to show a defect in this bigger study.  It is because they have changed the light spectral curve.  We actually realize this almost by accident in one of our earlier trials where we didn't realize still yet that hey it really plays a difference, the brain is really sensitive to different spectral curves.  And we test for both in a kind of constructed devices based on this light boxes that you define that those standard measure how you define that kind of light power.  And we didn’t realize then we kind of got that hey why did this group of patients, individuals react to this really well?  They didn't react although they are very similar patient groups.  When we took the devices, they soon realized that whey they measured the similar locks defined led lights they were totally different spectral curves.  Then we figured that these spectral curve, and that started the huge matrix of different indications on different spectral curves and that type of testing. 

Dr.  Killgore: The way that we're doing it in our studies is all through the eyes but it's not through the visual system though.  What's fascinating about this whole process is that there are different kinds of receptors in the eyes.  Some of them are involved in vision and other ones, we actually didn't know about until about 10 years ago that they even existed.  These are basically called intrinsic photoreceptive retinal ganglion cells.  These are type of cell that there's quite a few of them in the retina of the eye but only some of them seem to be responsive to specific wavelengths of light especially blue.  So it’s the blue wavelengths that stimulate these melatonin sensitive cells and they don't project back to your occipital cortex the way that the rest of the visual system does. 

We all went to school.  We all heard about the rods and the cones.  That's how we see things, the rods and cones take that information and send it back to your occipital cortex and then the occipital cortex turns it into a visual image.  But about 10 years ago or so it was discovered that there is this third type of receptor and these receptors project to other parts of the brain.  And one of the prominent projections is to the suprachiasmatic nucleus of your hypothalamus which is basically the regulator of your sleep wake cycle.  And so that led to the whole idea that maybe that's what this system is for is to help and train and regulate that circadian sleep wake pattern.  When people are exposed to light and most of our research is focused on blue, we see that it stimulates these areas.  It affects the super suprachiasmatic nucleus and then affects how the pineal gland basically produces melatonin.

There could be other effects of light as well.  There's some evidence out there.  I haven't done research on but other investigators have looked at red light and there's some evidence that red light may actually have some alerting effects in certain ways.  We've been also looking at the non-melatonin aspects of light recently and my post-doc just recently published a paper looking at the effects of blue wavelength light on direct activation of the brain without going through the melatonin system in a sense.

What we did in that situation was we brought people into a room and we had them sitting in a darkened room and they just got shined either an amber colored lights or a blue colored light for half an hour right onto their visual system that we took them out of the room immediately and put them into a brain imaging scanner and did fMRI scans while they engaged in some different kinds of working memory tasks.  What we found was that just being exposed to that blue light half an hour ago was enough to still enhance brain activation within an area of the brain called the dorsolateral and the ventrolateral prefrontal cortex.  So these are areas that are involved in working memory and behavioral control.  They turned on more when people engaged in this task if they had the blue light than if they had the amber colored light.

Jesse: Did you have a control group that got no special light whatsoever?

Dr.  Killgore: We didn't use any with no light.  We just gave them the amber as a control because we assumed that was going to have anything.  And in fact it didn’t.  So just sitting there with this amber color didn't seem to do anything to the brain.  By the time we got the scanner it had no effect.  And then we correlated that with how much activation was in the brain with their performance, and we found that the greater activation in the blue group in those prefrontal areas was actually associated with better performance.  So they were able to solve the working memory problems faster and more accurately in combination.  They did more correct items per minute if they had received the blue light than if they had not.  So over other sleep deprivation work focused in on risk taking behavior.  We looked at moral judgment during sleep deprivation.

Jesse: The moral judgment I think would be really interesting and it may be breaking apart what moral judgment is versus just judgments in general because those could be fuzzy terms.

Dr.  Killgore: Well, we basically utilized somebody else's task.  So there is a person out at Harvard University.  His last name is Green.  And basically he had done a number of studies using this particular moral judgment task.  What they did basically is they showed people three different kinds of dilemmas, non-moral dilemmas, trying to decide if you should take bus or the train to get to work.  And so you just have to make a decision.  There's no moral component to it.  No emotional component to it.  It’s just a cold cognitive decision.  Or you have a moral kind of dilemma.  And the classic one that I always tell people about is what most people have heard of in their philosophy class.

Jesse: Okay.  So this is that moment that I warned you about where for about the next minute he's going to be explaining the trolley problem, if you're already familiar with the trolley problem, you can probably hit fast forward on your podcast app for a moment.  And if you're not it is super interesting and worth learning what it is.  So just hang in here.

Dr.  Killgore: The idea is you got this trolley speeding down the tracks and it's going to run five people over and it's going to kill those five people.  Thankfully you're just standing by the side of the railroad track next to a lever and you can pull that lever and it's going to cause the trolley to shift onto a second set of tracks where there's only one person standing.  If you do nothing the trolley is going to kill the five people.  If you pull the lever it will veer it off and it will save the five people but it will kill the one.  So the question is what's the appropriate response in that situation.  What should you do morally to do the right thing.  Most people would say that they would pull the lever.  It would kill one person but it would save five.  So morally that would be the right decision.  This particular task that Green had come up with also had a third condition which he called a moral personal dilemma.  Basically it's an up close and personal situation that's much more emotionally engaging and what's happening now is you've got the trolley coming down the tracks again heading right toward those same five people.  But this time you're standing on a bridge overlooking the tracks and right in front of you as this very large person.  And if you walk up behind that person and you push them off the bridge they'll fall to their death landing on the tracks stopping the trolley and saving the five people.  So the question is would you push the person to their death in order to save the five people.

And most people when you ask them that one will say no way, I wouldn't do that.  I wouldn't go that far.  I wouldn't push a person to their death.  And so the philosophical question is always why do they say yes in one situation but no and the other when it's the same outcome.  What it comes down to is the emotional intensity of the situation.  The bridge situation you have to put your hands on another person that's a very emotionally engaging situation whereas the other one you're very distant.  It's like dropping a bomb on a foreign country from 30,000 feet is very different than blowing a bomb up where you can see it happen to the people.  So we used all three of these dilemmas and gave them to a sample of military personnel when they were well-rested and then we tried it again after they'd been awake for two full days without any sleep at all.  Basically what we found was that sleep deprivation really had no effect on the non-moral dilemmas that you could decide whether to take a bus or train to get to work just as quickly when you were sleep deprived as you did when you were well-rested.

So sleep deprivation doesn't necessarily impair all decision making.  But when we look at the moral impersonal dilemma the pulling the lever, what we also found was people were just as good at doing that when they were sleep deprived as they were when they're well-rested.  So it didn't affect that either.  What it did affect was the moral personal dilemmas, the emotionally charged dilemmas.  In that case, people took several seconds longer to make the decision.  In those situations and they were much more likely to push the person off the bridge when they were sleep deprived than they were well-rested.

Jesse: Interesting.  I guess we kind of view that as making the tough decision, the hard call. 

Dr.  Killgore: Sophie's Choice.  We actually had some things that actually were those Sophie's Choice kind of things where they were terrible decisions that people had to make.  You smother the baby to save the village from the Marauders that are coming over the hill.  Horrible decisions that people would have to make.  And many of them actually got very irritated taking these tests because they didn't like even having to answer those kind of questions but we felt that it was so important that we really look at the effects of this because it could have implications for police officers, for military personnel.  When you're sleep deprived there's a chance you may make a different decision than you would have had you been well-rested.

Jesse: It's interesting though.  I mean that almost makes you wonder if there might be like a hidden therapy in there for people that feel like they're typically too wimpy in their choices and that they wish they could be the tough as nails person.  Is sleep deprivation a way of sort of nudging yourself towards that more tough as nails mentality?

Dr.  Killgore: It could be because what we're finding also that that same study was also related to emotional intelligence too.  So again it taps into the emotional side of things.  We found that the people with high levels of emotional intelligence above average levels, they didn't change in their emotional choices.  They were the moral choices, they made the same decision either way.  But it's those who had lower levels of emotional intelligence, they actually changed their positions more in those situations.  It's like they couldn't really rely on their emotional intelligence to help them through it.  And so you know it's a possibility I've never tested it but maybe it might actually give you the ability to stand up and say something when you need to.  Part of it is because your peripheral cortex just doesn't inhibit a lot of what you're going to do in those situations too.

Jesse: What do you want to study next?  What are some of the nagging questions for you about how we sleep and how we might sleep better.

Dr.  Killgore: We've got a couple of different directions we're heading right now.  We've had some ongoing studies where we're using that light therapy that I was telling you about to actually try to help people recover from brain injuries.  We've only just started working on this so we haven't published our results yet but the idea is that if you're getting better sleep it helps you to actually clear out some of the neurotoxins in your brain.  There's some evidence that it can help to enhance development of myelin again within the brain.  So what we wanted to do was to help people to recover faster by using these light therapies to re-entrain the circadian rhythm thereby improving sleep and perhaps actually bringing about some changes in brain structure and brain function. 

So that maybe if they'd had a concussion this might actually help them recover faster.  And some of our preliminary data that we haven't published yet but is very exciting is starting to show that there are some brain changes both structurally and functionally when people go through about six weeks of treatment with some of these light devices.  It's helping them sleep better a little bit but in particular it seems to be leading to some structural changes within the brain that we're hoping are being associated with actual recovery.  And then we'll get another study that we're hoping to get started up with in the next few months where we're going to be looking at basically stress responses when people are sleep deprived.  And we're going to be putting them through an overall stressful situation as they stay up throughout the night.  And we're trying to see if we can use personality traits to predict who is going to be able to function better under stress in those kinds of situations.  A lot of these are because we know these are problems that our service members are dealing with when they are coming back from their deployments.  And all overarching goal and all the work that I do is really to try to take care of our service members who experience either exposure or trauma or a concussion of some sort. 

And so PTSD is a big issue that we’re trying to work on right now.  One model of PTSD, not the only model but one is the idea that some of what has happened may be related to a conditioned fear response.  I wouldn’t say it’s necessarily the best model but it’s the one that we’re working on and so what we’re looking at can be used as fear conditioning experiment.  Then essentially extinguish the fear response that a person has, follow it up with the light therapy and get them to sleep better.  Our hope is that sleep is actually going to help consolidate and generalize that fear extinction, memory more effectively for those people with post-traumatic stress.  So we’re testing that theory up now to see how it plays out.

Written by Hannah Sabih
Hannah believes there's nothing 8 hours of sleep and some kale can't cure (yes, she's from California). She's an avid runner, reader, and traveler, who brings you the latest and greatest in neuroscience via our social media channels.
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