Mar 262011
 

This post is in initial build-out status and may change.

General Information: Wikipedia entry. Note: Melatonin is a natural hormone that is also available as a supplement. The Evidence Summary and Score below assess the benefits and/or risks of melatonin levels in general.

Studied Uses: General health, cancer

General Health

Melatonin - General Health Evidence Summary - http://sheet.zoho.com

Overall Score: 2.18

Behind the Score:

Evidence for beneficial effects of relatively high melatonin levels is piling up across many types of studies and in relation to many disorders and biomarkers. Experiments have variously studied sleep quality 1, ALS (Lou Gehrig’s disease) 2, behavioral disturbances in Alzheimer’s 3, and brain damage 4. Perhaps the biggest hope for melatonin is as a cancer protective, discussed below because the number of studies warrants a separate section.

That said, the majority of studies comprising the overall score assessed test subjects’ natural melatonin levels (based on working shift hours, natural sleep-and-wake cycles, or physiological factors such as BMI and age) rather than the value of melatonin supplementation. If planning to supplement, talk with a doctor to find the right dose, since it is quite possible to take too much melatonin. Even better may be increasing your own body’s production of melatonin through lifestyle changes.

For example, natural melatonin production may be suppressed by exposure to bright lights (such as computer screens) after dark. 5 And it doesn’t take that much light to suppress melatonin production. 6 Another study showed that women who routinely “were not asleep at or after 1:00 a.m.,” the time of highest melatonin production, had higher serum estradiol levels, which may be a risk factor for cancer. 7 Overall, light exposure at night appears to pose risks for humans, which this study from the Journal of Pineal Research does an excellent job of summarizing.

Warnings and Special Notes: Melatonin’s greatest effects may be in its naturally occurring form. Melatonin supplementation has not been sufficiently studied in pregnancy and breastfeeding.


Cancer

Melatonin - Cancer Evidence Summary - http://sheet.zoho.com

Overall Score: 1.96

Behind the Score:

Some studies that looked at natural melatonin levels found correlations between higher melatonin levels and lower cancer risk 8 9, although one prospective study in premenopausal women found no association and another found an increased risk in the two years after baseline measurement of melatonin levels and a decreased risk over the longer term. 10 (Researchers speculated that this result could reflect preexisting sub-clinical illness affecting baseline melatonin measurements in some women — in other words, they were already sick at the beginning of the study and their melatonin levels were high as a result!) Notably, most studies of melatonin supplementation did not identify a positive effect on cancer risk, recurrence risk, or biomarkers. For example, a double-blinded, randomized controlled trial of melatonin supplementation in postmenopausal breast cancer survivors found improved sleep with melatonin supplementation but not improved biomarkers 11 (caveat: The study was small and short-term, with 95 women studied over 4 months). Another study of melatonin use in people with metastatic brain cancer found no benefit; in fact, the people given melatonin supplements had shorter median survival times than historical control data would predict. 12 Conversely, it increased survival times for lung cancer patients who did not respond to initial chemotherapy. 13

Warnings and Special Notes: Melatonin’s greatest effects may be in its naturally occurring form. Melatonin supplementation also has not been sufficiently studied in pregnancy and breastfeeding.


What Now? More rigorous study is warranted, especially of supplementation.

What Can I Do? You can work to boost your body’s melatonin production by:

  • Going outside for at least half an hour each day and letting full-spectrum light reach your eyes (yes, that means no glasses or contacts during that time)
  • Getting to bed relatively early and at a consistent time;
  • Sleeping in a dark room or using a good eye mask;
  • Keeping the lights off if you need to get up in the middle of the night (be careful, though!);
  • Decreasing exposure to blue-spectrum light (such as your computer screen or television, or blue-spectrum fluorescent lights) after dark;

One possible mitigation for late-night computer users: Try Flux, an application for Windows, Mac OS X, and Linux that adjusts screen brightness and color spectrum to match the time of day.

All of this may be a tall order, since the modern urban lifestyle features a lot of bright lights and late nights. If you’re unwilling or unable to make lifestyle changes, or you’ve tried and think they aren’t helping enough, you can talk with your doctor about trying a melatonin supplement. This might or might not be right for you, but getting the dose right is definitely important.

 

Notes:

  1. Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effects. Journal of Sleep Research, 2007.
  2. Reduced oxidative damage in ALS by high-dose enteral melatonin treatment. Journal of Pineal Research, 2006.
  3. Decreased Melatonin Levels in Postmortem Cerebrospinal Fluid in Relation to Aging, Alzheimer’s Disease, and Apolipoprotein E-{epsilon}4/4 Genotype. The Journal of Clinical Endocrinology & Metabolism, 1999.
  4. The protective role of melatonin in experimental hypoxic brain damage. Pediatrics International, 2005.
  5. Effects of VDT tasks with a bright display at night on melatonin, core temperature, heart rate, and sleepiness. Journal of Applied Physiology, 2003.
  6. Minimum light intensity required to suppress nocturnal melatonin concentration in human saliva, Neuroscience Letters, 1998.
  7. Light Exposure at Night, Urinary 6-Sulfatoxymelatonin, and Serum Estrogens and Androgens in Postmenopausal Japanese Women. Cancer Epidemiology, Biomarkers and Prevention, 2008.
  8. Urinary Melatonin Levels and Postmenopausal Breast Cancer Risk in the Nurses’ Health Study Cohort. Cancer Epidemiology, Biomarkers and Prevention, 2009.
  9. Urinary Melatonin Levels and Breast Cancer Risk. Journal of the National Cancer Institute, 2005.
  10. Urinary 6-Sulphatoxymelatonin levels and risk of breast cancer in premenopausal women: the ORDET cohort. Cancer Epidemiology, Biomarkers and Prevention, 2010.
  11. Randomized trial of oral melatonin supplementation in breast cancer survivors. Proceedings of the American Association for Cancer Research, 2010.
  12. Randomized Phase II Trial of High-Dose Melatonin and Radiation Therapy for RPA Class 2 Patients With Brain Metastases (RTOG 0119). International Journal of Radiation Oncology, 2007.
  13. Randomized study with the pineal hormone melatonin versus supportive care alone in advanced nonsmall cell lung cancer resistant to a first-line chemotherapy containing cisplatin. Oncology, 1992.

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