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Melatonin: Helpful or Hurtful?

Melatonin is probably better known as a dietary supplement than a naturally occurring hormone. Can it be helpful to take an over-the-counter (OTC) melatonin supplement when you’re having trouble sleeping or would that be doing more harm than good to your natural sleep-wake cycle?

What does melatonin do?

Darkness prompts the brain’s pineal gland to start producing melatonin, while light causes production to stop. This process syncs up our sleeping and waking cycle with night and day. Naturally occurring melatonin not only helps us fall asleep, it also promotes quality rest1.

Taking over-the-counter (OTC) melatonin

The occasional use of OTC melatonin doesn’t interfere with our body’s production of the hormone nor has it been found to cause any major medical complications or serious side effects. But it can have minor side effects, from daytime sleepiness, headaches and dizziness to bizzare dreams and excessive movement during sleep2. As we age, we produce less melatonin, which is why OTC melatonin appears to be most effective in middle-aged and older adults. A study of prolonged release melatonin, a formulation that mimics the way the body naturally makes melatonin throughout the night, validated this finding. While younger, middle-aged and older insomnia patients all found melatonin significantly improved sleep quality, morning alertness, ability to fall asleep and quality of life, the 55- to 80-year old group particularly benefited3.

Melatonin and light exposure

Light exposure, whether from the environment or a light emitting device, suppresses our ability to produce melatonin, which is why light at night can cause problems falling and staying asleep and can lead to poor quality sleep4. Light exposure can be used therapeutically, however, to help treat mental health issues like bipolar disorder, depression and seasonal affective disorder, as well as sleep issues like circadian rhythm disorder. The effectiveness of these treatments suggests the importance of proper levels of melatonin for good mental health and sleep5. For those who are blind and unable to benefit from the light cues that normally regulate the sleep-wake cycle, OTC melatonin use can be helpful6.

Final thoughts

While taking OTC melatonin hasn’t been shown to cause major side effects, using it regularly can mask any number of sleep disorders — sleep apnea, restless legs syndrome, etc. — that would then go undiagnosed and untreated. In addition, there is limited information on any adverse effects of its long-term use6. As with any supplement, you should always consult your doctor before taking OTC melatonin. And examine your sleep habits to be sure you’ve done everything you can to get a good night’s sleep before taking any kind of sleep aid.
  1. Diethelm K, et al. (2010) Hormone Research in Paediatrics.
  2. Besag FMC, et al. (2019) CNS Drugs.
  3. Wade AG, et al. (2007) Current Medical Research and Opinion and Wade AG, et al. (2011) Current Medical Research Opinion.
  4. Wams EJ, et al. (2017) SLEEP and Cho JR, et al. (2013) Sleep Medicine.
  5. Valdes-Tovar M, et al. (2018) British Journal of Pharmacology and Pail G, et al. (2011) and Bumb JM, et al. (2016) Comprehensive Psychiatry and Valdes-Tovar M, et al. (2018) British Journal of Pharmacology.
  6. Besag FMC, et al. (2019) CNS Drugs.

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