What is melatonin and how does it affect sleep?

You are probably aware that getting a good night’s sleep is crucial to your daily performance, whether that means focus, alertness, or even emotional stability.

Unfortunately, it is also far from uncommon to face obstacles in getting high-quality shut-eye, with as much as 36% of UK adults reporting sleepless nights at least once a week. While insomnia is the most widely acknowledged sleep disorder, awareness of DSWPD (disordered sleep-wake phase disorder) has grown in recent years. This condition is directly related to the disruption of our cyclical body clock — otherwise known as the circadian rhythm — due to a deficiency of melatonin, our ‘sleep hormone’.

As a result, supplements for melatonin have become a sought-after treatment to combat sleep-related problems. Meanwhile, more and more information has emerged around the relationship between our exposure to light and the levels of the hormone in our body. Here we’ll explore the essential facts about this vital component of our sleep cycle, and what we can do to influence it.

What is melatonin?

Melatonin is a naturally occurring hormone in our body. It is secreted by the pineal gland, a pea-sized part of the brain which philosophers once upon a time considered to be the ‘seat of the soul’. While the jury is still out on that one, what we do know is that melatonin is associated with how the central nervous system influences the sleep-wake cycle.

One of the physiological effects of melatonin is to facilitate sleepiness. It doesn’t put us to sleep per se, but it does make us rather tired. The best way to think about it is that it is not the force which, as it were, knocks you out, but that which informs your body that it’s night-time so that you can rest easier. It works by binding to receptors in the brain, helping to inhibit the levels of hormones associated with wakefulness, such as dopamine.

Melatonin is also theorised to have significant benefits for our development and cognition. In children, melatonin is much more prevalent in waves throughout the day, and has been associated with inhibiting the onset of puberty.

How does melatonin affect sleep?

According to neuroscientist Andrew Huberman, if sunlight reaches our eyes soon after we wake up, it “triggers a neural circuit that controls the timing of cortisol and melatonin”. This is important for gaining feelings of wakefulness early in the day, as the presence of light is aligned to our circadian rhythm.

However, this rhythm can be disrupted by exposure to light at times that do not reflect our external environment. A classic example of this is jet lag: it takes most of us a short while to readjust our body clocks after flying for hours through different time zones. This is because our circadian rhythm is lagging behind our levels of dopamine and cortisol, as a result of our irregular overstimulation by light.

Since melatonin helps prime you to fall asleep, if there is not enough produced in your body at night-time, you may have difficulty getting high-quality sleep. This is because the body’s natural production of melatonin responds to stimuli from our environment. Times of low light levels, such as during evening darkness, prompt the release of this sleep hormone. Research has found, furthermore, that compared to green light wavelengths blue light is a particularly acute suppressor of melatonin, shifting circadian rhythms by twice as much!

How can I get better quality sleep?

It would be useless to substitute natural light in the morning with blue light from your phone or laptop screen. Equally, it is detrimental to your sleep quality and pattern, and therefore your overall health. This is because the wavelengths of blue light have the most powerful impact on the body’s internal clock. Since blue light neutralises the effects of melatonin, Huberman continues, “if you're looking at your phone at 1 AM, you might as well have flown to Abu Dhabi”.

Get natural sunlight exposure

In short, our bodies are designed to take in ultraviolet and other high wavelengths, such as those found in fluorescent lights and mercury vapour lamps (i.e. in street lighting). However, we should only be exposed to a limited amount at night. Instead, sleep experts recommend getting natural sunlight exposure when you wake up, and deliberately watching the sunset in the evening, to regulate your sleep-wake cycle. This helps to programme your body to emit the sleep hormone at the right time of day.

Avoid blue light where possible

Avoid using your computer, smartphone or tablet in the hours before bed. With Ocushield products, you can filter out harmful blue light from screen devices at all times of the day, and further limit its impact on your sleep-wake cycle, along with the potential retinal damage and vision impairment. If you regularly do shift work at night time, blue-blocking lens filters will be especially helpful for allowing you to fall asleep by letting your circadian rhythm adjust to changes in light exposure. You might even be an avid reader who can’t find time during the day, so a low blue-light oculamp can help you optimise sleep while keeping the comforts of a good book.