By Virginia Gurley, MD, MPH

MB (Marc Braman, MD, MPH):
Today we’re talking about melatonin basics. Good to have you back with us Dr. Gurley. In an earlier session, we talked about light at night and how it disturbs sleep by blocking the release of a chemical in the brain called melatonin. What is the difference between the brain’s melatonin and melatonin in supplements?

VG (Virginia Gurley, MD, MPH):
Well, the main source of melatonin in the brain comes from a pea-sized area deep in the brain called the pineal gland. And, at night when you’re in the dark, this gland releases melatonin into the fluid that bathes the brain, this fluid is called cerebrospinal fluid, and so the amount of melatonin in the brain tissue is much higher than when you take a melatonin supplement.

MB:
Ok, so much higher than in the bloodstream. So, what does melatonin do to improve the quality and restorative effects of sleep?

VG:
Melatonin seems to have many positive effects on sleep, but one of the main effects is triggering increased blood flow to the skin. When this happens, your skin gets warm, letting off heat, which then allows your body core temperature to go down and cool.

MB:
Yea, so this is an interesting phenomena, I know it’s really hard to get to sleep if my hands and feet are cold. I still remember my grandfather telling me bedtime stories of growing up on his farm in New England and they would heat up rocks on the stove and wrap them in blankets and things and put it at their feet so they could get to sleep in a really cold house. If I’m understanding this correctly, the cold hands and feet keep my skin from warming which doesn’t let my core temperature cool down. Is that right?

VG:
You got it.

MB:
Ok, good. So some conditions like diabetes and high blood pressure affect blood flow in the skin, is that why poor sleep is common with these conditions?

VG:
Well, that’s at least part of the picture. Any condition that decreases blood flow in the skin can disturb the skin warming processes that trigger sleep. Even high levels of stress hormones can block nighttime skin warming, and then the normal sleep triggering process is disturbed.

MB:
So why would the body core cooling be important to the restoring and repairing processes that are supposed to happen during sleep?

VG:
Well, it’s not fully understood, but research has shown that nighttime melatonin release is linked to another brain substance called Brain Derived Neurotrophic Factor, or BDNF, and this substance is key to repair and replacement of injured brain cells. Other research suggests it’s the temperature shift that signals BDNF release in the brain.

MB:
Ok, i’ve read studies about melatonin being used to treat brain injury. Is that related to this BDNF release?

VG:
Well, there is still more we need to learn about how melatonin is linked to brain repair processes, but some studies have shown better recovery from brain injury when melatonin and prolonged sleep are part of the treatment.

MB:
So, this would make sense why people after concussion just want to do a lot of sleeping. Why can’t we get these same effects by taking melatonin supplements?

VG:
Well, when you take melatonin pills, the amount that gets to your brain is very small. It’s thought that the melatonin pills that dissolve under your tongue, they’re labeled sublingual, they might give you higher levels of melatonin in the brain but it’s still not as much as what your pineal gland produces.

MB:
Ok, so if I’m going to take a melatonin supplement, it’s better to get the under the tongue or sublingual pills. What else should I know?

VG:
Well, it’s better not to take melatonin every night because there aren’t long term studies to show whether that causes the pineal gland to make less of your own natural melatonin. Also, 0.5 mg supplements seem to be as effective for increasing sleep as 3 mg pills. But most importantly, avoiding bright light, and especially blue coloration light at night, is the best way to protect your body’s own melatonin release.

MB:
Excellent, so some very practical things to understand are melatonin and how we can manage that. So, hot water bottles, hot rocks, they’re are all good, get our hands and feet warm, warm bath, warm shower, deal with the stress. And if we’re going to use melatonin as a supplement, use a small dose, under the tongue, and probably for a short period of time. Thank you so much, Dr. Gurley.

VG:
Thank you, Dr. Braman.

Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Chang A-M, Aeschbach D, Duffy JF, Czeisler CA. Proceedings of the National Academy of Sciences of the United States of America. 2015;112(4):1232-1237. doi:10.1073/pnas.1418490112.

Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans. Gooley JJ, Chamberlain K, Smith KA, et al. The Journal of Clinical Endocrinology and Metabolism. 2011;96(3):E463-E472. doi:10.1210/jc.2010-2098.

High Sensitivity of Human Melatonin, Alertness, Thermoregulation, and Heart Rate to Short Wavelength Light. Carotene C, Munch M, Kobialka S, et al. The Journal of Clinical Endocrinology & Metabolism. 2005;90(3):1311-1316. doi:10.1210/jc.2004-0957.

Spectral modulation attenuates molecular, endocrine,  and neurobehavioral disruption induced by nocturnal light exposure. Rahman SA, Marcu S, Shapiro CM, Brown TJ, Casper RF. Am J Physiol Endocrinol Metab. 2010;300:E518-E527, 2011.

Role of Melatonin in Traumatic Brain Injury and Spinal Cord Injury. Naseem M, Parvez S. The Scientific World Journal. 2014; doi:10.1155/2014586270.

Virginia Gurley, MD, MPH

Dr. Gurley is Founder and President of AuraViva, a health education organization dedicated to increasing accessibility and efficacy of healthy lifestyle strategies. She has over 25 years experience designing and implementing health promotion and disease prevention programs and has served 15 years in physician executive positions. She is faculty at the American College of Lifestyle Medicine and member of American Academy of Sleep Medicine.

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