#140: Melatonin, Sleep, and Your Pineal Gland

August 05, 2016

Quick — tell us everything you know about the pineal gland.

It’s probably not much, right?  That’s ok, because until surprisingly recently, scientists didn’t know much either.

But we now know quite a lot, including the pineal gland’s essential function producing melatonin.  Dr. Richard Wurtman, Cecil H. Green Distinguished Professor emeritus at the Massachusetts Institute of Technology, talks to us about his work studying the pineal gland and melatonin.

The Third Eye

Your pineal gland is a small endocrine gland in the brain.  It was first studied in relation to amphibians (turns out it lightens frog skin) where it’s linked to the parietal eye (also known as the “Third Eye”), which regulates the circadian rhythm based on levels of light in the environment.

But scientists didn’t think it had any function in mammals — considering it an atrophied, vestigial photoreceptor — and certainly nothing to do with melatonin (which was only discovered in the late 1950s).

Eventually, however, Dr. Wurtman and colleagues discovered that if you put animals in constant, bright light, their pineal glands would shrink, and melatonin production would be severely curtailed.

So, it turns out, the pineal gland is still like a third eye, although it’s no longer a photoreceptor, which is why light is first detected by your retina before that information is passed on to the pineal gland.

High At Night and Low In the Daytime

Once the connection between light and the pineal gland was discovered, it was easy to piece together the role of melatonin.

Environmental levels of lightness and darkness entrain your circadian rhythm, so you sleep when it’s dark and are awake when it’s light.  This, in turn, affects melatonin production, so that melatonin is actively produced at night, with very little produced in the day time.

Since levels are high at night, Dr. Wurtman began wondering if melatonin had something to do with sleep onset.  Spoiler alert:  It did.

Melatonin promotes sleep onset and maintenance, i.e. falling and staying asleep.

Your Aging Pineal Gland

Among other indignities that occur as you age, your pineal gland is calcifying, meaning it’s producing less melatonin at night.  This is why older adults have a hard time staying asleep — they produce enough melatonin to fall asleep, but not enough to stay asleep throughout the night.

It’s a pretty easy condition to fix:  just supplement with melatonin.

But wait, it’s not that easy.  Why?  Because the correct dose of melatonin is fairly small (0.3mg) but your body very quickly metabolizes melatonin.

So, if you take 0.3 mg of melatonin before bed, you’ll easily fall asleep, but it won’t be enough to keep you asleep throughout the night.

So just take a much higher dose, right?  Nope.

Melatonin Desensitization

Older adults do need to take melatonin every night, but they’re taking doses that are much too high.

Melatonin is often sold in pills of 3 mg (and even higher), which is 10x the recommended dose (here’s a time-release melatonin pill in the correct dose).  The good news is that melatonin is extremely non-toxic, so you’ll never overdose.

But you will blow out your melatonin receptors, so that melatonin supplements stop being effective.  When you have so much extra melatonin in your system, your melatonin receptors become desensitized and stop reacting to all that extra melatonin.

Companies are able to sell such high dosage melatonin because the FDA decided to classify melatonin as a dietary supplement, resulting in little oversight.

Dr. Wurtman points out what a mistake this is, since melatonin is clearly a hormone, not a dietary supplement, and no food has ever been found to raise melatonin levels.

Bottom line

The correct dose of melatonin is 0.3 mg.  Taking the lowest effective dose will avoid desensitizing your receptors.

Tune into the episode for more on melatonin, plus how different light wavelengths and meal times affect your sleep.

PS:  Don’t stay in the dark — sign up for our weekly Brain Breakfast!

Read Full Transcript
Show Notes
  • 00:00:42

    Melatonin with Dr. Richard Wurtman

  • 00:01:46

    This Week in Neuroscience: Frigatebirds sleep in mid-flight

  • 00:06:20

    News and audience interaction

  • 00:08:43

    What is a neuromodulator?

  • 00:10:24

    Discovery of the pineal gland’s function and how melatonin works

  • 00:20:43

    Differences in melatonin levels as we age, sleep efficiency, and desensitization

  • 00:25:05

    What doses should people be taking?

  • 00:28:35

    How does excess melatonin get cleaned out of our systems?

  • 00:29:30

    Melatonin and light sensitivity

  • 00:33:29

    The relationship between melatonin and insulin production

  • 00:34:14

    Is melatonin an antioxidant? (Not really…)

  • 00:36:19

    Ruthless Listener-Retention Gimmick: Setting free the words trapped in our heads


  1. cormac crisp says:

    Speaking about mind reading, you should check out the Bodytalk system. Its considered to be energy based medicine where the practitioners use neuromuscular biofeedback to ask your body about its health status. In the sessions that I’ve had, it feels like the practitioners had an uncanny ability to read my thoughts. Bodytalk also has a cortices technique to help balance your brain. I think it would be interesting if you did
    an episode about it.

    1. Jesse Lawler says:

      Cormac — I have to admit, ever since reading Blink by Malcolm Gladwell, I tend to credit unconscious processing for all sorts of “uncanny” stuff that people are able to do. Sometimes it’s frustrating that our ability to do things trails way behind our ability to accurately explain *how* we can do things… (My suspicion is that energy medicine — to the extent it works — falls under this “bad explanations for observed results” category.) I’ll see what I can find out about Bodytalk; I haven’t heard of it before, but thanks for the pointer. 🙂

  2. Richard says:

    Great episode. Thanks Jesse! I’m suggesting the time-release melatonin for my mum. The description fits her to a tee!

  3. Bobby says:

    As a longtime sufferer (15+ years) of sleep-maintenance insomnia, I really want to give the Life Extension melatonin a try. But here’s my dilemma:

    I live in Phoenix, AZ. It’s SO HOT here during the summers that you simply can’t receive anything in the mail that is heat-sensitive. Not until about November, when it starts to cool to a reasonable temperature.

    Do you have any idea if the Life Extension melatonin would survive a few days in an extremely hot mail truck, then in an even hotter metal mailbox? I really don’t want to wait 3 more months to give this stuff a try.

    1. Jesse Lawler says:

      Hi there Bobby — Two thoughts: a) Why not buy it at a local health food store, where (hopefully) they’ve had more end-to-end temperature control during shipping? b) Why not give it a try through the regular mail and see? The worst that happens is that you’ll get some physiologically inert melatonin — a waste of money, but the stuff isn’t expensive. One brand name of melatonin should be the same as another (unless there is some special buffering to create a delayed release), so I’d expect even if you can’t find the exact brand, shopping at a local vitamin store you’ll be able to find an equivalent.

  4. Missy says:

    Thank you for this podcast. I couldn’t understand why when I took melatonin, after 3 days, I laid wide awake. This episode has cleared up my confusion. For future, I’ll spend the extra money and purchase the 0.3mg dosage and save the 3mg for transatlantic flights.

    Thanks again. Love what you do. Keep them coming.

    1. Jesse Lawler says:

      Thanks Missy. Or you could just buy the larger dosages and crush the pills up a bit. I’ve seen 1mg pills for sale that you could (inexactly) break into approximate-thirds. 🙂

  5. Sean says:

    Great show about melatonin, I heard many years ago that 1.3mg is the highest anyone would ever need to supplement with, although I don’t recall where I heard that. Perhaps when using it as a one-off to combat jet lag, that would be the maximum amount. I wouldn’t worry too much about it being damaged by heat. Life extension ships pretty fast in my experience, usually less than 5 days when I’ve ordered it from them direct

  6. Rick Hart says:

    Do you know if your body becomes desensitized to it, how long it would take for this to reverse. Or is reversal impossible?

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