What does melatonin do and how does it work?
What is melatonin?
- Melatonin is a hormone that our body makes naturally. It is produced by the pineal gland in the brain, but also found in other areas, such as the eyes, bone marrow, and intestines (1). OIt's often called the sleep hormone because high levels can help us fall asleep. However, melatonin itself won't knock us out.
- It simply lets our body know it's dark so we can relax and fall asleep more easily(2). Melatonin supplements are popular among people suffering from insomnia and jet lag. You can buy melatonin supplements without a prescription in many countries.
How does melatonin work?
- Melatonin works in tandem with our body's circadian rhythm. Simply put, the circadian rhythm is our body's internal clock. It allows us to know when it is time to :
- Sleep
- Wake up
- Eat
- Melatonin also helps regulate body temperature, blood pressure, blood sugar, body weight, and levels of certain hormones (3, 4 ). Melatonin levels start to rise when it's dark outside, signaling to our bodies that it's time to sleep. It then decreases in the morning, when it is light outside, to encourage awakening (5). For example, it binds to receptors in our brain to reduce nerve activity. It can also reduce levels of dopamine, a hormone that helps us stay awake and is involved in certain aspects of our eyes' day-night cycle (6, 7).
- Although the exact mechanisms of melatonin are unclear, research suggests that these processes may help us fall asleep. Conversely, daylight modulates melatonin production, which lets our bodies know it's time to wake up (8).
- Many factors can cause low melatonin levels at night, such as alcohol consumption, smoking, caffeine consumption, shift work, aging, certain medications, and exposure to too much light at night, including blue light (9, 10). Taking a melatonin supplement can help counter low levels and normalize our internal clock.
Taking melatonin for sleep may help
- Strong evidence suggests that taking melatonin before bed decreases sleep latency the time it takes you to fall asleep — while increasing total sleep time (11, 12, 13).
- A review of 11 studies demonstrated that taking melatonin before bed reduced sleep latency by almost 3 minutes and increased total sleep time by approximately 30 minutes, compared to a placebo (11).
- Another analysis of 23 studies of people with sleep disorder-related illnesses found that melatonin significantly reduced sleep disturbance and sleep latency while increasing sleep duration and quality (13). This analysis concluded that melatonin was not useful for improving sleep in people with mental disorders or brain diseases such as Alzheimer's disease, other studies have shown otherwise (14, 15, 16).
- Additionally, melatonin can counteract jet lag, a temporary sleep disorder. Jet lag occurs when your body's internal clock is out of sync with a new time zone.
- Shift workers may also experience symptoms of jet lag because they work during hours normally used for sleeping (17).
Melatonin can help reduce jet lag by synchronizing our internal clock with the time change (18). - Before trying melatonin, however, it's best to establish healthy sleep habits, such as establishing a consistent sleep schedule, limiting alcohol and caffeine intake, and reducing your exposure to light and electronic devices before bed.
