The secret to a good night's sleep

Date

Evelyn Lewin

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Photo: Getty

If you've ever struggled to fall asleep (and who hasn't?), then you might have been tempted by a quick-fix solution. But there is a simpler answer: light. "Light exposure trains your circadian [sleep-wake cycle] rhythm," says Simon Joosten, a respiratory and sleep medicine physician at Monash Health and Epworth Sleep Centre. This is because light exposure affects the production of melatonin, a hormone necessary for sleep. Light receptors located at the back of the eye tell the brain to stop making melatonin during the day. Conversely, darkness stimulates melatonin release, signalling sleep.

"I don't think it's a matter of 'Heaps of light in the day equals way more sleep at night,' " says Joosten. "It's more that the amount of light exposure during the day will help determine when your block of sleep will happen." In other words, if you get enough light at the right time, you'll fall asleep more easily. And the earlier you fall asleep, the more hours you can snooze before your alarm clock buzzes.

An ideal way to light your day is to head to the great outdoors. A study published in the journal Current Biology last month monitored eight people during a normal week. They were then sent camping, where artificial light and electrical devices were banned. After one week in nature, all participants (even the night owls) were

Salute the sun … if you get enough natural light at the right time, you'll fall asleep more easily.

Salute the sun … if you get enough natural light at the right time, you'll fall asleep more easily. Photo: Getty Images

in sync with the day's natural rhythm. Behavioural factors played a part - you can't surf the web all night if there's no computer - but the role of natural light was deemed pivotal. However, you don't need to kiss city life goodbye to improve your sleep; you just need the right kind of light at the right time.

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Morning
A key reason the campers slept better is because they were able to "rise and shine". "Bright light exposure early in the morning has the greatest effect on circadian rhythm," Joosten says. At home, however, unless you plan to wake when the sun has fully risen (and your bedroom is facing east), the amount of exposure isn't that great.

While sleeping with the blinds open may help, Joosten suggests a morning walk, saying the length of time needed outdoors relates to the intensity of light that day. On a bright morning, 15 minutes should suffice, whereas you may need half an hour if it's overcast.

Alternatively, Joosten advises ditching your sunnies as you drive to work, as they lessen the intensity of light received. He says light exposure through windows - though weaker than direct outdoor light - still has a significant effect on melatonin levels.

Afternoon
Exposure to natural light throughout the day is important, too. New research, published in an online supplement of the journal Sleep in June, found office workers with windows received 173 per cent more white light exposure than their windowless colleagues. They also slept an average of 46 minutes more per night and scored higher on sleep quality measures.

Joosten says windowless workers probably slept more poorly because they weren't getting enough daylight to train their circadian rhythm. And standard electrical light alone is not intense enough to affect melatonin levels.

But even light-deprived workers can up their melatonin levels. "Midday is when natural light is at its most intense, so you get more bang for your buck," says Joosten. He suggests going for a walk or simply eating lunch outside at that time for a powerful boost of daylight.

Night
At night it's all about avoiding bright lights. While your bedside light is unlikely to cause sleeplessness, backlit devices can. This is because they emit blue light, which has a strong effect on suppressing melatonin release.

But if switching off the phone or tablet is unappealing, research presented in June by the US-based Mayo Clinic found dimming your device, and holding it at least 35 centimetres from your face when using it in bed, can reduce its negative effect on melatonin.

That said, Joosten advises switching off such devices at least half an hour before bed and banishing them from the bedroom altogether. Keeping your bedroom tech-free will not only optimise melatonin release, it will also quieten your mind, leading the way to a great night's sleep.