Melatonin, our rest and repair hormone


Just as many of us need "light therapy" in order to cope with SAD (Seasonal Affective Disorder), I would bet that many more of us actually need "dark therapy", and some of us probably could use a combination of both.  In today’s world, we often don’t spend much time outdoors in the day, and we tend to live by artificial light at night.

Every cell of our body is sensitive to light and darkness, and now that we no longer tend to live according to the rising and setting sun, our health is suffering.

Melatonin, synthesized from the neurotransmitter serotonin and secreted by the pineal gland in the brain, is one of the victims of our current modern lifestyle. It has a big job to do – to help us recuperate from our day, and prepare us for tomorrow.

It is activated by darkness and inhibited by light, so before the invention of the light bulb when we actually lived according to the cycles of daylight and darkness, melatonin had adequate time to get its nightly job done. When it gets dark outside, it is supposed to be “melatonin time”.

Turning on the lights at night and staying up late tricks our body into thinking it is day, keeping the day hormone levels (like cortisol) higher. Then, when we finally go to bed and turn out the lights, melatonin may not have enough time to do its job before daybreak.

And if the bedroom is not completely dark – an outdoor street lamp is shining through the window onto our skin for example, melatonin may not be activated at all.

This is why working night-shift is so devastating to health.  Many scientists believe that inadequate melatonin is a primary cause of many diseases like type 2 diabetes, heart disease and cancer, because then there is nothing to stop the run-away train that too much stress causes in the body.

The light of yang is no longer balanced by the dark of yin hormonally (cortisol / melatonin), in the CNS (sympathetic / parasympathetic), psychologically (stressed / relaxed) and even on a societal level (work / play). Work and productivity are valued highly in our society, whereas people that live a more balanced life are often considered "slackers" or lazy.

Melatonin is a very powerful antioxidant that works in watery as well as fatty environments, and unlike other antioxidants, melatonin is able to cross the blood brain barrier.  So, at night, melatonin’s job is to sop up those free radicals before they do too much damage to other tissues.

Melatonin helps control the menstrual cycle in females, controls estrogen levels (thereby playing a key roll in preventing hormonal cancers like breast, ovarian, uterine and even prostate cancer), and is important in controlling circadian rhythms.

Melatonin is also synthesized by the immune system for its many roles within that system, including enhancing T cell production. Melatonin even seems to be involved in regenerating injured tissue, as seen in this study on rat degenerated intervertebral disks.

Melatonin, among other things, helps us sleep (or is supposed to!)

As someone who has a real problem sleeping, I completely disagree with the advice frequently given to insomniacs to get up, get out of the bedroom and read or do something if one can’t sleep because that would entail turning on a light, which would then shut down melatonin, resulting in less rest and repair happening.

Getting up certainly won’t help you get to sleep! I know from experience what putting in a full day of work feels like after lying in bed awake from 10pm to 7am, but turning on a light I think will just mess up the hormones more. You certainly don’t want to fire up cortisol at 2 in the morning!

Listening to relaxation CDs may be helpful. What helped me enormously when I wasn’t sleeping four out of seven nights for months on end, was listening to the relaxing Insight CD, which lowered my brain waves to delta, so even though I wasn’t sleeping, I was getting some rest. I honestly think that without that CD I would have had to cancel many a work day.

If you suffer from insomnia, it may be very tempting to rely on melatonin supplements to help you sleep. Personally, I think that apart from very occasional use to aid in jet-lag recovery, this is a bad idea because if you are providing external melatonin, your body will sense it in the blood stream and stop producing it.

Over time your pineal gland will shrink, and you may no longer be able to produce your own melatonin, which would leave you stuck taking the supplement for life. Far better to decrease sympathetic load (reduce your stressors), get lots of light during the day, and then lots of dark time at night.

Frequently addressing cortisol circadian-rhythm problems will also make a big difference, as high cortisol levels at night make it pretty hard to sleep! (Small aside, for those of you are keeping track – cortisol does not suppress melatonin, but melatonin does not suppress cortisol either.

That means you can have high cortisol levels when its dark and you are lying awake stressing, but melatonin is not active when it’s light. Therefore, cortisol is still the kingpin, as it is functional 24/7.)

In the winter time especially, our bodies probably need a good 9.5 hours in complete darkness.  No light, TV sets, computers or night lights at all. Get that TV out of the bedroom! 

That does not mean that we must be in bed sleeping for that length of time – dark time can provide an opportunity for meditation, contemplation or listening to music for example. This way it is easier to quiet the mind before trying to sleep.

If in the night you need to use the bathroom, don’t turn on the bathroom light. Use a red night light (not white, blue or green), or a flashlight with a red bulb.

Black-out drapes can make a huge difference to the darkness of a bedroom, or in a pinch you can put foil on the windows. Many people have said that they didn’t realize they were sleeping poorly until they slept in a completely darkened room.

Related Tips
Breast / prostate cancer prevention
Light pollution messes with your hormones
Is going to bed too late making you fat?
The autonomic nervous system and fat loss
Adrenal fatigue

Formby and Wiley; Lights Out! Sugar, Sleep and Survival Books, New York, NY, 2000

Smolensky and Lamberg; The Body Clock Guide to Better Health  Holt and Company, New York, NY, 2001.

Davis, Scot et al.
Light at Night and Working the Graveyard Shift Linked to Increased Risk of Breast Cancer
Journal of the National Cancer Institute October 2001

Blask, David, MD, PhD et al.
Melatonin-Depleted Blood from Pre-Menopausal Women Exposed to Light at Night Stimulates Human Breast Cancer Xenografts in Nude Rats
Cancer Research 65, 11174-11184, Dec. 1,  2005.

Verkasalo, P. et al. Sleep Duration and Breast Cancer: A Prospective Cohort Study Cancer Research 65, 9595-9600, Oct. 15, 2005.

Harder, Ben. Bright Lights, Big Cancer Science News Online Jan. 7, 2006.

Sainz. RM et al.
Melatonin reduces prostate cancer cell growth leading to neuroendocrine differentiation via a receptor and PKA independent mechanism
Prostate 63(1) 29-43, April 1, 2005.

Moretti RM et al. Antiproliferative action of Melatonin on human prostate cancer LNCaP cells Oncol Rep 2000 7(2):347-351.

Fraschini F. et al. Melatonin involvement in immunity and cancer Biol Signals Recept 1998, 7(1): 61-72.

Spiegel, Karine et al. Sleep Loss: A novel risk factor for insulin resistance and Type 2 diabetes Journal of Applied Physiology 99: 2008-2019, 2005.

Broadway J, et al.
Bright Light Phase Shifts the Human Melatonin Rhythm during the Antartic Winter
 Neuroscience Letters 79 (1987): 185-189.

McMillen, I.C., et al., "Melatonin and the Development of Circadian and Seasonal Rhythmicity" Journal of Reprod. Fertility Supplement 49 (1995):137-146.

Van Cauter, Eve, et al., "Modulation of Glucose Regulation and Insulin Secretion by Circadian Rhythmicity and SleepJournal of Clinical Investigation 88, (September 1991) 934-942.

Van Cauter, Eve et al. Impact of sleep and sleep loss on neuroendrocrine and metabolic function Horm Res. 2007;67 Suppl 1:2-9. Epub 2007 Feb 15.

Von Treuer, K., et al. Overnight Human Plasma Melatonin, Cortisol, Prolactin, TSH, under Conditions of Normal Sleep, Sleep Deprivation and Sleep Recovery Journal of Pineal Research 20, no. 1 (January 1996): 7-14.

Wehr, Thomas A., et al.
The Duration of Human Melatonin Secretion and Sleep Respond to Changes in Day Length (Photoperiod)
 Journal of Clinical Endocrinology and Metabolism 73, no. 6 (1991): 1276-1280.

Wehr, Thomas A., et al.
Suppression of Men’s Responses to Seasonal Changes in Day Length by Modern Artificial Lighting
 American Journal of Physiology 269, no. 38 (1995): R173-R178.

Brown R., et al
Differences in Nocturnal Melatonin Secretion between Melancholic Depressed Patients and Control Subjects
 American Journal of Psychiatry 142. no. 7 (July 1985):811-816

Copyright 2007 Vreni Gurd


  1. marvin willhite said,

    February 5, 2010 @ 8:06 pm

    i am a 50 year old man who can not go to sleep early and always getting up early in the morning will this product help me. i also have high blood pressure

  2. Vreni said,

    February 6, 2010 @ 1:10 pm

    Hi Marvin,

    I don’t recommend melatonin supplements as then your body will stop producing the hormone naturally. You can try the recommendation above of turning out all the lights including TV and computers at around 10pm in order to help your body ingrain a more healthy circadian rhythm, which in turn may help you sleep.

    The other suggestion I have is that you get your hormones tested – cortisol, testosterone, possibly thyroid – through a functional medicine doctor. Sleep problems and hormone problems go hand in hand, so addressing the issue this way can often be successful. Biohealth Diagnostics may be able to help you with this. Contact them!

  3. Luis said,

    December 20, 2015 @ 7:07 pm

    Unfortunately, I am too familiar with the impcat of early start times. Our school district’s high school start time is among the earliest in the nation (7:10 a.m.) and my 15 year old son struggles with it on a daily basis. Despite my best efforts, he rarely gets enough sleep because his biology is changing and that’s affecting his sleep patterns. I’m proud to say I signed the petition. I hope this national initiative is successful – for the health and safely of my children.

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