Smartphone insomnia: Why checking your phone before bed spoils your sleep

Most of us experience insomnia at some point in our lives, finding it difficult to drift off and stay asleep despite having plenty of opportunity to. Typical causes of insomnia include stress and anxiety, but did you know that your gadgets could be to blame, too?

Our sleepiness and wakefulness throughout the day and night is regulated by our circadian rhythm. This is essentially our body clock, creating physical, mental and behavioural changes that occur in our bodies over a roughly 24-hour cycle. Circadian rhythms are found in most living things, including animals, plants and many tiny microbes, and are created by natural factors in the body. However, they also respond to signals from the environment, such as light, so that we remain in sync with the Earth’s rotation.

All forms of light, both natural and artificial, affect our body clock, as when the photosensitive retinal ganglion cells in our eyes detect light, they send this information to the suprachiasmatic nucleus (SCN) – the group of nerves in the brain that controls circadian rhythms. When light is detected, the SCN will delay the production of melatonin, a hormone that sends us to sleep. However, the retinal ganglion cells have been found to be particularly sensitive to the blue light with a short wavelength of 480 nanometres emitted by most computer, smartphone and tablet screens. Exposure to a lot of this type of light in the hours before we go to bed has been proven to suppress melatonin levels, making it difficult for us to get to sleep.

How light affects your ability to sleep
How light affects your ability to sleep

Blocking blue light

The best way to reduce your exposure to blue light is to avoid staring at a screen in the two hours before you go to bed. Instead illuminate the room with the warmer longer-wavelength light from regular incandescent bulbs or even candles.

However, if you just can’t resist staring at your computer or phone before bed, then there are ways that you can do so and still get a good night’s sleep. Wearing special glasses with amber-coloured lenses will filter out blue, low-wavelength light, allowing you to stare at your screen for as long as you like. Companies such as Uvex (uvex-safety.co.uk) make blue-blocking glasses and goggles in a range of styles. Alternatively, you could use computer software such as f.lux (justgetflux.com) and smartphone apps such as Twilight (play.google. com) that automatically adjusts your screen to filter out blue light between sunset and sunrise, replacing it with a softer red light.

Sleeping records

Shortest

Giraffes require less sleep than any other mammal, typically getting 20-30 minutes per day for five minutes at a time.

Average

The amount of sleep we need varies from person to person, but we typically require about eight hours per night.

Longest

Koalas are some of the heaviest sleepers, clocking up approximately 15 hours of snoozing per day.

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