Sleep is often on our minds, and we can frequently find ourselves looking for ways to improve our sleep quality and quantity. Recently, melatonin has thrown its hat into the ring to achieve this. With this in mind, Dr David Garley has created a blog exploring melatonin and its role in sleep.
Melatonin is a natural hormone produced by the brain. Why melatonin is relevant to sleep comes back to the key systems for controlling sleep, including the circadian rhythm.
The circadian rhythm is also known as the internal body clock. It has evolved because, as humans, we need our bodies to behave differently depending on the time of the day. For example, we rely on light to carry out our activities, therefore meaning we have evolved to be more active during daylight hours than at night.
Our body’s pattern of behaviour continues with its internal momentum. Many body processes align with the circadian rhythm, but the control of sleep and wake is probably the most well-known. There are different hormones associated with the wake phase and sleep phase of the circadian rhythm. It is through these hormones that our various body functions are controlled.
During the wake phase, the dominant hormone is cortisol, which helps our body carry out many of its ‘wake’ functions, whereas the main hormone during sleep is melatonin. Melatonin signals to your body that it is entering the sleep phase and should prepare for it. It’s produced by a part of the brain called the pineal gland and is released into the blood, where it can work all over the body.
Melatonin influences other body processes, such as lowering your body temperature and blood pressure. There is also research suggesting that melatonin improves the immune system’s ability to fight off infections. It works as an antioxidant and can reduce the rate at which your body ages.
The melatonin level is almost undetectable during the day but suddenly peaks around two hours before your normal bedtime, as you get ready to move into the sleep phase of your circadian rhythm.
Melatonin is the hormone present at nighttime, and as such, it is influenced by levels of light. Bright light, which you normally associate with daytime, inhibits melatonin production. Alternatively, other activities, such as exercise, can influence melatonin production.
Melatonin production also changes over your lifetime. Production begins in childhood and peaks as a young adult, then drops around the middle age mark and can lower drastically in older adults. The hormone itself is made from an amino acid called tryptophan. Your body can’t generate tryptophan – it’s known as an essential amino acid and so it must come from your diet. Foods that are rich in tryptophan include turkey and certain types of cherries.
It certainly makes sense to think that taking melatonin will improve sleep. However, the reality isn’t as straightforward.
Firstly, melatonin relates to only one of the two systems of controlling sleep (the circadian rhythm), so altering melatonin levels isn’t the answer by itself, which leads us nicely to our next point.
Melatonin is responsible for signalling to the body that it is entering the sleep phase rather than causing sleep itself. The way this signal is given is through a sudden production of melatonin, which we know is influenced primarily by light and daytime activity.
Difficulties in clearly transitioning from the wake phase to the sleep phase of your circadian rhythm are less due to an overall deficiency in melatonin but more as a result of uncoordinated exposure to the stimuli that trigger its production – namely light, exercise and an inconsistent waking and sleep time. These reasons go a long way to explaining why taking extra melatonin has not been shown to have a significant impact on sleep either from taking the melatonin tablets themselves or through taking the tryptophan-rich supplements or foods.
Instead, what has a larger impact is properly coordinating the stimuli that influence its production. However, a few exceptions relate to the population groups that produce less melatonin – children and older adults.
Research studies have shown that supplements can help when you aren’t producing much melatonin. Children, especially those experiencing neurodiversity, such as autistic spectrum conditions and ADHD, often have less robust circadian rhythms. Research has also shown that in the over-55-year-old group, more gentle improvements in sleep can be experienced with melatonin. There is a third group of people shown to benefit from melatonin tablets, and these are people suffering from jet lag.
Jet lag is a type of circadian rhythm disorder where flying across multiple times zones, your body’s internal rhythm is at odds with the local time zone. Your body has a fantastic ability to adjust to a new time zone, but it takes several days to do this – usually one day for every time zone travelled, and during this time, you can feel very sleepy and fatigued.
Exposure to the stimuli that influence your circadian rhythm – light and exercise, can help with this adaptation, but evidence has also shown that taking a type of melatonin tablet in the short-acting form can simulate the sudden peak of melatonin that occurs a couple of hours before your usual bedtime, and can bring your circadian rhythm forwards – or backwards – depending on the time that you take it. This should always be done together with coordinated exposure to light and exercise.
In some ways, sleep is a complex process and is controlled by many different factors; melatonin is just one of these factors.
Perfect sleep, unfortunately, doesn’t exist; if your sleep is generally okay but there’s room for improvement, then sleep hygiene is an evidence-based approach to do this.
Sleep hygiene involves promoting the wake phase of your circadian rhythm so the sleep phase arrives more naturally; this is best achieved by waking up at the same time each day and taking advantage of sunlight where possible. Towards the end of the day, sleep hygiene involves preparing yourself for sleep by enjoying a relaxing wind-down routine and avoiding stimulants such as caffeine too close to bedtime.
It’s also recommended that you ensure your bedroom is the best place for sleeping by being cool, dark and quiet with a comfortable mattress. For most of us, these steps are likely to influence our sleep more than melatonin supplements.
However, if your sleep troubles are more consistent and has a significant daytime impact, this may be insomnia, which is a specific diagnosis. The first-line treatment for insomnia is cognitive behavioural therapy or CBTi. If you are over 55 years old or younger with neurodiversity, then you could speak to your GP about a trial of melatonin tablets.
If you would like more advice on how to improve your sleep, then please visit www.thebettersleepclinic.co.uk
