Sleep Essentials: Light
The invention of artificial light in the 19th century and the ever-increasing use of light-emitting tech has had a massive influence on our natural relationship with light and dark. This in turn has bought highly disruptive challenges to our sleep.
What is the role of light in our sleep?
In order for us to see the world, we need light. As such, over thousands of years, our eyes have developed to allow us good vision. But it wasn’t until 1998 when a scientist from Oxford discovered that light also has powerful effect on our ability to sleep.
The scientist and his team made an exciting discovery: Melanopsin. Found behind our eyes, these cells absorb light during the day and send off signals to a specific area of the brain called the suprachiasmatic nucleus (SCN). In response, the SCN suppresses the production of a hormone called melatonin, also known as our ‘sleepy hormone’. This causes us to become more alert and ready to face the day!
On the other hand, an absence of light during the night gives the brain the green light to pump out lots of melatonin, initiating the process whereby the body prepares for sleep. This includes muscle relaxation, increased drowsiness, and a small drop in body temperature allowing us to fall asleep and stay asleep.
Research has shown that exposure to light for even 2 milliseconds during the night is enough to confuse the brain that it’s day time and cause it to begin the process of waking you up.
As useful as this may be during the day, light exposure at the wrong time, i.e. scrolling through Instagram at 1am, can make falling asleep harder and can even cause frequent and prolonged awakenings during the night. This is why mobile phones should be kept out of the bedroom, especially for those suffering from insomnia.
An even more significant consequence of frequent exposure to light during the night is that it can inhibit the naturally timed rise of melatonin. This delays the onset of the body’s transition to sleep, which may also affect subsequent nights, which may cause havoc on your long-term sleep patterns.
Preparing for sleep
The body needs time to prepare for sleep. An hour before bed, dim overhead lights or turn them off completely, and use calming, warm-light side lamps instead.
As part of your wind-down routine, avoid the use of electronic devices and leave your mobile phone outside the bedroom. Turn off the television, and leave your tablet aside.
If you are finding it difficult to stay away from your tech, change your devices’ settings to minimise your exposure to blue light. iPhone users can use Night Shift, whilst Android users can download Twilight to dim their screens at night. Blue filter screens, glasses, and contact lenses with HEV filters can also help those who can’t resist the urge to bring their tech along in bed.
You also need to keep a dark environment when you are sleeping. Even though our eyes are closed, our eyelids are too thin to make us immune to the effects of light. Make sure you close the curtains, which should preferably be blackout curtains, and use an eye mask to keep your nighttime light exposure to a minimum.
If you tend to go to the bathroom often during the night, use motion-sensor lights with red bulbs. Unlike the blue light emitted from smartphone screens, red light is less disruptive to sleep.
In the same way as dimming down helps you fall asleep, an increasingly bright environment in the morning will help you wake up. Open the curtains as soon as you wake up, or use sunrise-imitating lamps that gradually brighten up your bedroom in the early hours of the day. This will let your brain know that it’s day time and ensure that you are awake, alert, and ready to go!
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