March 15, 2022
Written by: Greer Prettyman
It’s estimated that up to 50% of adults experience symptoms of insomnia including difficulty falling asleep or staying asleep at night1. Especially during the ongoing COVID-19 pandemic, people across the world have struggled with sleep problems2. For many, the pandemic brought high levels of stress and anxiety, disruption of normal schedules and routines, and an increase in bedrooms serving double duty as workspaces, all of which can make it harder to get high-quality sleep. When faced with a frustrating inability to sleep, over-the-counter sleep aids can be a tempting solution. One of the most common sleep supplements is melatonin, sold at US drug stores in the form of pills, gummies, teas, and even chocolate bars. Is melatonin a cure for tossing and turning or is it nothing more than a placebo?
What is melatonin?
Melatonin is a hormone that the body naturally produces. Human sleep cycles are regulated by fluctuations in levels of different hormones throughout the day and night. Some, like melatonin, increase in the evenings and help to promote sleepiness3. Others rise in the morning and keep us awake during the day. This fluctuation over a 24-hour period is referred to as a circadian rhythm.
A part of the brain’s hypothalamus called the suprachiasmatic nucleus (SCN) controls circadian rhythms. The SCN is responsive to light entering the eyes, receiving inputs from melanopsin-expressing retinal ganglion cells that are sensitive to blue light in particular. These retinal cells send signals to the SCN via the retinohypothalamic tract, allowing our circadian rhythms to synchronize to the cycles of light and darkness in the environment3. The SCN controls secretion of the hormone melatonin, which is produced in the pineal gland. When light hitting the retina signals the SCN, secretion of melatonin into the body is inhibited, so that during daylight hours we remain awake and alert (Fig 1). Then, as it gets dark outside, the SCN signals for melatonin secretion to begin, helping the brain to wind down and prepare for sleep. This strong relationship between light and the body’s natural production of melatonin is one reason that light from looking at your phone or computer right before bed can make it more difficult to fall asleep. If you do look at screens before bed, wearing glasses that block blue light can help promote normal melatonin release at night by reducing activation of the retinal ganglion cells.
Is melatonin a sleeping pill?
Melatonin supplements give your body a little extra melatonin, in addition to what is produced in the brain. The additional melatonin acts in the same way as the naturally-made hormone, taking advantage of the circadian rhythms already at work. A melatonin supplement simply amplifies the signal that it’s time to prepare the brain for sleep. In this way it’s quite different than most prescription sleeping pills, like Ambien or Lunesta, which are sedatives that enhance activity of the neurotransmitter GABA4. A sedative will cause you to fall asleep by reducing neural activation in many parts of the brain. In contrast, melatonin will not make you fall asleep, but will engage the body’s normal sleep-producing rhythms to help you feel sleepy.
Is it effective?
The FDA does not regulate supplements and vitamins in the US, so the efficacy of melatonin supplements has not been studied in clinical trials the way a sleeping pill or any other drug would be. Many scientists, though, have researched the effects of melatonin on sleep. An analysis technique called a meta-analysis can be used to combine the results of many individual studies to make broader conclusions about a topic. In one such meta-analysis, the efficacy of melatonin compared to a placebo was measured in research studies in over 1500 people. The analysis revealed that on average, people who took supplemental melatonin fell asleep 7 minutes earlier and slept 8 minutes longer during the night5. Sleep quality was also improved by melatonin compared to placebo. Although the increases in sleep time and quality were modest, these results suggest that melatonin can give your night’s sleep a bit of a boost.
Is it safe?
If you’re considering trying a sleep aid, melatonin is usually a safer option than a prescription sedative. According to the Mayo Clinic, side effects of melatonin supplements can include headache, dizziness, nausea, and drowsiness6. Melatonin can also interact with other medications, resulting in either decreased effectiveness of those medications or increased side effects of melatonin, both of which can be dangerous. Just like with any supplements, it’s best to consult a doctor before adding melatonin to your routine.
One benefit of melatonin over prescription sedatives is that melatonin has a lower risk of being addictive. Prescription sedatives that act on the GABA system are dependence-forming, leading to sleep difficulties and withdrawal symptoms after discontinuing use7. Melatonin, on the other hand, has not been found to be addictive and it can be used long-term without a decrease in effectiveness8.
If you’re having trouble sleeping, taking some melatonin before bed might help you drift off faster or sleep a little bit longer. But it’s not the only way to improve your sleep; there are many ways to promote quality sleep, like avoiding caffeine late in the day, reducing stress through meditation or therapy, and avoiding screen time in the hours before bed. However you do it, getting a good night’s sleep is a sure way to take care of your brain.
- Cleveland Clinic, https://my.clevelandclinic.org/health/diseases/12119-insomnia
- Alimoradi Z, Broström A, Tsang HWH, Griffiths MD, Haghayegh S, Ohayon MM, Lin CY, Pakpour AH. (2021) Sleep problems during COVID-19 pandemic and its’ association to psychological distress: A systematic review and meta-analysis. EClinicalMedicine.
- Pandi-Perumal SR, Cardinali DP, Zaki NFW, Karthikeyan R, Warren Spence D, Reiter RJ, Brown GM. (2022) Timing is everything: circadian rhythms and their role in the control of sleep. Front Neuroendocrinol.
- Bomalaski MN, Claflin ES, Townsend W, Peterson MD. (2017) Zolpidem for the Treatment of Neurologic Disorders: A Systematic Review. JAMA Neurol. 2017 Sep 1;74(9):1130-1139.
- Ferracioli-Oda E, Qawasmi A, Bloch MH. (2013) Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One. 8(5):e63773.
- Mayo Clinic, https://www.mayoclinic.org/drugs-supplements-melatonin/art-20363071
- Schifano F, Chiappini S, Corkery JM, Guirguis A. (2019) An Insight into Z-Drug Abuse and Dependence: An Examination of Reports to the European Medicines Agency Database of Suspected Adverse Drug Reactions. Int J Neuropsychopharmacol. 22(4):270-277.
- Xie Z, Chen F, Li WA, Geng X, Li C, Meng X, Feng Y, Liu W, Yu F. (2017) A review of sleep disorders and melatonin. Neurol Res. 2017 Jun;39(6):559-565.
Cover Image from Unsplash
Figure 1 Created with Biorender
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