By Dr. Mercola
The hormone melatonin plays many important roles in your health, from helping you sleep better to strengthening your immune system, slowing down brain aging, reducing migraine attacks, protecting bone mass, and preventing cancer.
Lack of sun exposure during the day combined with artificial lighting late into the night disrupts your biological clock and hence, your melatonin production, and this disruption can provoke a number of adverse health effects.
In fact, melatonin has been the subject of preclinical research on over 100 different disease applications, many of which go hand in hand with your need for sleep.
Melatonin for Sleep and Beyond
Your master biological clock resides in the suprachiasmatic nucleus of your brain (SCN), which is part of your hypothalamus. Based on signals of light and darkness, your SCN tells your pineal gland when it's time to secrete melatonin, and when to turn it off.
In scientific studies, melatonin supplementation has been shown to help people fall asleep faster and stay asleep, experience less restlessness, and prevent daytime fatigue.
Keep in mind that you may only need a very minimal dose. I recommend taking only 0.25 mg or 0.5 mg to start, and adjusting upward from there. Taking higher doses, such as 3 mg, can sometimes make you more wakeful instead of sleepier, so start low and adjust your dose as needed.
Melatonin has also been found to reduce the effects of jet lag when traveling across multiple time zones.1 And children suffering with eczema, a condition that oftentimes prevents good sleep, may also get more shut-eye with melatonin supplementation,2 according to recent research.
Interestingly, melatonin also helped dampen the severity of the eczema, hinting at its anti-inflammatory effects. However, the benefits of melatonin go far beyond sleep. Three specific areas I'll address in this article are its role in depression, multiple sclerosis, and cancer.
Normalizing Your Circadian System Helps Alleviate Depressive Symptoms
Your melatonin level inversely rises and falls with light and darkness, and both your physical and mental health is intricately tied to this rhythm of light and dark. When it's dark, your melatonin levels increase, which is why you may feel tired when the sun starts to set.
Conversely, when you're exposed to bright artificial lighting at night, including blue light emitted from TVs and electronic screens, you may have trouble falling asleep due to suppressed melatonin levels.
Light exposure when you wake up at night can also be problematic as I explain in my video above. However you don't have to stumble around as red and orange wavelengths will not suppress melatonin production.
You can use a red light to guide you to the bathroom. If you have a clock in your bedroom make sure it has a red LED display. Blue would be the worst as it is the one that shuts down melatonin most effectively.
Winter Blues SAD
Seasonal affective disorder (SAD, also called "the winter blues") is associated with lack of sun exposure, and scientists generally recommend full-spectrum light therapy over SSRIs like Prozac or Zoloft for this condition.
Interestingly, recent research suggests light therapy may be preferable even for major depression, outperforming Prozac in those with moderate to severe depression. One of the reasons it works so well likely has to do with the fact that bright light helps reset your biological clock, or circadian rhythm.
Melatonin supplementation can help do this to a certain extent as well, but not as effectively as exposure to bright light during daytime. Light may also work in a way similar to antidepressants by regulating neurotransmitter function.
Light Therapy — More Effective Than Prozac
The study3,4,5,6,7 in question set out to compare the effectiveness of light therapy alone and in conjunction with the antidepressant fluoxetine (Prozac).
The eight-week long trial included 122 adults between the ages of 19 and 60, who were diagnosed with moderate to severe depression. The participants were divided into four groups, receiving:
- Light therapy (30 minutes per day upon waking using a 10,000 lux Carex brand day-light device, classic model) plus a placebo pill
- Prozac (20 mg/day) plus a deactivated ion generator serving as a placebo light device
- Light therapy plus Prozac
- Placebo light device plus placebo pill (control group)
In conclusion, the study found that the combination of light therapy and Prozac was the most effective — but light therapy-only came in close second, followed by placebo.
That's right, the drug treatment was the least effective of all, and LESS effective than placebo! At the end of the study, remission was achieved by:
- Just over 19 percent in the Prozac only group
- 30 percent in the placebo group
- Nearly 44 percent in the light therapy only group
- Nearly 59 percent in the active combination group
How Melatonin May Aid in the Treatment of Multiple Sclerosis
Multiple sclerosis (MS) is an autoimmune disorder that, like SAD, has been linked to vitamin D deficiency from lack of sun exposure. Interestingly, recent research suggests that a drop in autumn and winter relapses may be linked to peak melatonin levels, which occurs during these darker months.
Conversely, spikes in relapses occurring during spring and summer — which tend to be less common but do occur — may be related to decreased melatonin levels. The research,8 led by neuroscientist Mauricio Farez at the Dr. Raúl Carrea Institute for Neurological Research, looked at 139 MS patients living in Buenos Aires.
Thirty-two percent of them experienced a reduction in relapses during fall and winter, compared to spring and summer. As reported by Scientific American:9
"Past research has shown that melatonin can have a protective effect against MS and that shift work, which disturbs melatonin production, can increase the risk of developing the disease. According to the authors, this research is one of the first to bring together epidemiological evidence with results from both human cells and animal models ...
[And it] may help to resolve a 'seasonal paradox' — MS flare-ups should decrease during warmer, brighter months when people receive more exposure to sunlight and thus produce more vitamin D, which also has anti-inflammatory properties. But some studies, including this one, show that relapses increase in the spring and summer pointing to the possibility that other environmental factors, such as melatonin levels, are involved."
To test their hypothesis, mice with autoimmune encephalomyelitis (the animal model of MS) received daily injections of melatonin. As a result, clinical symptoms were reduced, and harmful T cells, which are pro-inflammatory, were reduced, whereas regulatory T cells were increased. Similar effects were shown in petri dish experiments. As noted in the featured article:
"Melatonin regulates pathways central to the immune response, so these results may pertain to other autoimmune diseases, particularly where seasonal flare-ups occur, such as lupus and rheumatoid arthritis ..."
Melatonin's Role in Fighting Cancer
Cancer is another area where melatonin plays a major role. The evidence suggests it may be an important adjunct to cancer treatment,10 as it also helps protect against the toxic effects of radiation therapy. Cells throughout your body — even cancer cells — have melatonin receptors, and melatonin is in and of itself cytotoxic, meaning can induce tumor cell death (apoptosis). It also:11
- Boosts production of immune-optimizing substances such as interleukin-2, which helps identify and attack mutated cells that lead to malignant cancer
- Inhibits development of new tumor blood vessels (tumor angiogenesis), which slows the spread of the cancer
- Retards cancer progression by activating the cytokine system, which helps inhibit tumor growth, and by stimulating the cytotoxic activity of macrophages and monocytes
- By its antioxidant action it also limits oxidative damage to DNA
- Inhibits tumor growth by counteracting estrogen. (At night, when melatonin production peaks, cell division slows. And when melatonin latches onto a breast cancer cell, it has been found to counteract estrogen's tendency to stimulate cell growth)
Melatonin has a calming effect on other reproductive hormones besides estrogen as well, which may explain why it seems to protect most effectively against sex hormone-driven cancers, including ovarian, endometrial, prostate, testicular and breast cancers12 — the latter of which has received the greatest amount of scientific attention. Some of the studies on melatonin for breast cancer include the following:
- The journal Epidemiology13 reported increased breast cancer risk among women who work predominantly night shifts
- Women who live in neighborhoods with large amounts of nighttime illumination are more likely to get breast cancer than those who live in areas where nocturnal darkness prevails, according to an Israeli study14
- From participants in the Nurses' Health Study,15 it was found that nurses who work nights had 36 percent higher rates of breast cancer
- Blind women, whose eyes cannot detect light and therefore have robust production of melatonin, have lower-than-average breast cancer rates16
- When the body of epidemiological studies are considered in their totality, women who work night shift are found to have breast cancer rates 60 percent above normal, even when other factors, such as differences in diet, are accounted for17
Melatonin May Improve Outcomes for Lung Cancer Patients
Other cancers may also benefit. In 2004, the Life Extension Foundation collaborated with Cancer Treatment Centers of America on the first clinical trial evaluating melatonin's effect in patients with lung cancer.
The results,18 which were published in conjunction with the 2014 American Society of Clinical Oncology Meeting, found a tumor response in just over 29 percent of those receiving melatonin at night, compared to just under 8 percent of those receiving it in the morning, and 10.5 percent of placebo recipients. As reported by Life Extension Magazine:19
"European clinical studies indicate that in patients with metastatic non-small-cell lung cancer, five-year survival and overall tumor regression rates were higher in patients concomitantly treated with melatonin than in those treated with chemotherapy alone. While no patient treated with chemotherapy survived after two years, five-year survival was achieved in 3 of 49 patients treated with chemotherapy and melatonin.
The researchers hope that similarly promising results could eventually convince mainstream medical practitioners to administer melatonin in combination with standard cancer treatment regimens to patients in earlier stages of cancer treatment."
The Importance of Light and Dark for the Synchronization of Your Body Clocks
Melatonin production is stimulated by darkness and suppressed by light, which is why your levels should be highest just prior to bedtime. This perfectly orchestrated system allows you to fall asleep when the sun sets and awaken refreshed with the sunrise, while also providing potential anti-aging and disease-fighting benefits.
If you're having trouble sleeping, which is a signal that your melatonin production is off, I suggest making sure you're sleeping in total darkness and to turn lights down at least an hour or so before bedtime. Also, avoid watching TV and using computers and other electronic gadgets at least an hour prior to bed.
All of these devices emit blue light, which will decrease your melatonin if you work past dark, so ideally you'd want to turn these items off once the sun goes down. If you have to use these devices you can wear yellow glasses that filter the blue wavelengths out and/or use free software like f.lux.
To light rooms at night, use "low blue" light bulbs that emit an amber light instead of the blue that suppresses melatonin production. An equally important factor is the quality of light you're exposed to during the day. Without sufficient sunlight during the day, your circadian clock may fall out of sync.
Most incandescent and fluorescent lights emit very poor-quality light. What your body needs for optimal functioning is the full-spectrum light you get outdoors, but most of us do not spend much time outside to take advantage of this healthy light.
Using full-spectrum light bulbs in your home and office can help ameliorate this lack of high-quality sunlight during the day, but cannot fully replace it. So do make an effort to go outside for at least 30 to 60 minutes each day during the brightest portion of the day, i.e. right around noon. This will help "set" your circadian clock and help you sleep better.
For Optimal Health, Make Sure You Sleep Well
Remember, when your circadian rhythms are disrupted, your body produces less melatonin, which means it has less ability to fight cancer, and less protection against free radicals that may accelerate aging and disease. So if you're having even slight trouble sleeping, I suggest you review my "33 Secrets to a Good Night's Sleep" for more guidance on how to improve your sleep-wake cycle.
If you've made the necessary changes to your sleep routine and find you're still having trouble sleeping, a high-quality melatonin supplement may be helpful.
The amount of melatonin you create and release every night varies depending on your age. Children usually have much higher levels of melatonin than adults, and as you grow older your levels typically continue to decrease. This is why some older adults may benefit from extra melatonin.
The same goes for those who perform night shift work, travel often and experience jet lag, or otherwise suffer from occasional sleeplessness due to stress or other reasons. Start with a dose of about 0.25 to 0.5 mg, and increase it as necessary from there. If you start feeling more alert, you've likely taken too much and need to lower your dose.