Sleep is constantly on our minds. Whether we’re planning how we can get enough of it, daydreaming about lunchtime naps or worrying about how tiredness might affect our health, it’s safe to say that sleep has a huge impact on our lives.

And there’s a hormonal reason we might be thinking about sleep so often. Melatonin is the hormone that helps to regulate the circadian rhythm, letting our bodies know when it’s time to go to sleep and wake up – making you feel dozy and dreaming of bed. 

“Melatonin is important because it helps regulate the timing of the circadian rhythm, synchronising the sleep-wake cycle to the light-dark cycle,” explains Dr Guy Meadows, co-founder and clinical lead at Sleep School. “This means that during each 24-hour period, we sleep and wake, and do every other biological process, at the right times.”

Melatonin, also known as the ‘sleep hormone’, is available in supplement form but it is naturally produced by the body. “The hormone is released into the bloodstream by the pineal gland, which is an endocrine gland located in the middle of the brain,” Dr Meadows explains.

Melatonin production is brought on by increased darkness and triggers feelings of tiredness, helping us regulate our sleep cycles. “The light-sensitive cells in our eyes are able to detect the changes in light, which, via our body clock, instruct the pineal gland to release melatonin,” says Dr Meadows.

This is one of the reasons why our body clocks are in line with the world’s natural rhythms of light and darkness. It’s also why experts advise against using digital devices before bed, as the light emitted from them can inhibit melatonin production, which could prevent you from being able to fall asleep.

It’s not just about when we stop seeing light, but also when we start. Our circadian rhythm kicks in again when we wake up, and it’s thought that morning sunlight sets a 12-hour timer in the body to start producing melatonin. 

Melatonin is beneficial in a number of ways. One of the most useful aspects of the hormone is that it helps us stick to a regular sleeping pattern, as the onset of darkness triggers its release. “Melatonin works to control the timing of your body’s circadian rhythm, which plays an important role in the regulation of sleep and wake patterns,” Dr Meadows says.

“Its release in response to darkness helps to synchronise the body clock to the current time zone, thus preparing the body for sleep,” he adds.

However, it’s important to remember that the release of the hormone won’t immediately send you to sleep, as many people believe. “Melatonin is not a sleep hypnotic or a sleep aid that puts you to sleep,” Dr Meadows stresses. “Instead, once in the bloodstream, melatonin works by placing the body in a state of quiet wakefulness, which in turn helps to promote sleep.”

“Quiet wakefulness” is the state your body will be in just before you fall asleep – when you feel relaxed and tired but haven’t quite dozed off yet. This means that melatonin actually promotes the feeling that happens just before we fall asleep – which is essential to help us get some shut-eye – rather than promoting sleep itself.

Melatonin is only one part of the very large parcel that is required to put your body to sleep and even when it’s released, other factors can still prevent you from sleeping.

In fact, melatonin might actually be more important for regulating our daily routines – making sure we go to bed and wake up at a consistent time – rather than promoting sleep. This is because melatonin is crucial in regulating our circadian rhythms, which helps us go to bed and wake up at a regular time by acting as an internal body clock of sorts. Melatonin is the key informant for our circadian rhythm, as darkness triggers the hormone and alerts our bodies at a semi-regular time each day that it’s time to get ready to sleep.

If you are struggling to fall asleep at night it could be down to a delayed release of your melatonin levels. “Some of your most commonly used devices can be messing with your melatonin levels,” Dr Meadows says. “Excessive time spent on your smartphone or laptop, especially at night, can cause your melatonin production levels to decrease because of unwanted light exposure.”

“Research shows that being on your device within two hours of bedtime inhibits melatonin production, resulting in delayed sleep onset,” he adds. “Additionally, and not surprisingly, too much caffeine consumption can also repress melatonin production.”

If you are worried about your melatonin levels, you can speak to your GP about having them checked via a blood test. Your GP might be able to prescribe you a supplement version of the hormone to deal with sleep issues like insomnia if they think it’s something you could benefit from.

However, there are many other issues that could be preventing you from sleeping, such as stress, anxiety or other lifestyle factors like diet or alcohol. Staying off your digital devices in the couple of hours before you go to bed isn’t a bad way to start dealing with any potential sleep issues, though, whether they’re related to melatonin or not.

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