Brain Health,

#175: Sleep, Light, and Your Brain

April 07, 2017

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 came up with a surprising solution.  Their “HumanCharger” device looks like an iPod with earbuds, but instead of playing music into the ears, it transmits bright light.  According to Valkee, just 12 minutes daily can be enough to reduce “winter blues” 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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