Man facing laptop, lacking good night's sleep
By Professor Grant Schofield

One of the most important things to understand in a good night’s sleep is melatonin.

Melatonin is a hormone. It’s suppressed during the day when you’re exposed to bright light, particularly light containing blue wavelength light. The blue wavelength light interacts with the eye, travels to the brain and sends the signal to keep melatonin down. As the blue light starts to fade out and it gets darker, melatonin will be peaking up.

Melatonin and cortisol work together. When you wake up, cortisol goes up, and you become invigorated and alert. When you’re getting to bed, melatonin goes up, and you feel sleepy. This is one of the reasons not to be too stressed before you go to bed because that will counteract things. It’s also the major reason why you want to be dialling down your exposure to bright blue wavelength light before you go to bed.

What’s crucial about melatonin is that it, for some reason, degrades in secretion as we get older. It peaks in childhood, and through adolescence and early adulthood, but as we get older we have less and less melatonin available.

In other words, the cycle and the pressure to sleep through the biology of blue light decreases as we get older.  This is one of the reasons why melatonin as a medication is ineffective in young, healthy people, but more effective in older people, because there may be a deficit.

Process S

There’s a second piece of sleep pressure called Process S, which relates to a neurotransmitter called adenosine. We have two innate biological sleep pressures. We get the blue light and the melatonin pushing us towards sleep, and we get another whole biochemistry to do with adenosine pushing us towards sleep. Adenosine keeps rising during the day and shunted back down and cleared out of the brain after a good night’s sleep.

Coffee and Napping against A Good Night’s Sleep

Interestingly, coffee blocks adenosine in the brain. You’ll still have the circadian rhythm, but you might be able to have some relief from tiredness early in the day from caffeine, or equally later in the day. However, this may prevent you from getting to sleep at night and may affect the quality of your sleep.

Napping reduces sleep pressure. It pushes adenosine back down, which may or may not be a good thing. Napping, in the siesta-type cultures, reduces heart attack risk by something like 40%. Napping seems to be a good thing, and perhaps all humans used to do that, but napping when you’re not that tired, for example, while watching TV at seven or eight o’clock at night, may ruin your whole night’s sleep.

Destructive Devices to A Good Night’s Sleep

If we’re talking about blue light and melatonin, we need to talk about the destructive effects of artificial light, especially for kids and adolescents. LED lighting, which includes computer screens, iPhones, iPads and other types of mobile devices, are very high in the proportion of blue light. This can really negatively affect our quality and quantity of sleep, especially in children.

Avoid exposure to these screens, at all costs, if you want a good night’s sleep.

Sure, there are ways of dealing with it. You can filter all the blue light out, and you can turn the lights out around your house. Getting off the device altogether is even better.

“There’s no place for electronic screen devices in a bedroom, especially the bedroom of a child or adolescent. They are destructive. You can tell yourself it’s okay, but it’s not. Get them out of there.”

If you want a good night’s sleep, move them. Simple as that. They’re destructive, and perhaps the cause of a whole bunch of things. Not only is the lack of quantity of sleep affected, but also the quality of sleep. So even if the teenager or child does get to sleep, they’re not getting the same cycling of deep sleep early on, and REM sleep later on as they otherwise would have got, which seems to be crucial for health. Sleep, biology, rhythms. There’s plenty happening here that’s interesting and has a direct effect on your life.


Find out more about Sleep from Professor Grant Schofield in our online course on Mind-Body Medicine.