Why light at night is messing with your mind
How many hours a day are looking at a screen? This includes TV, computers, ipads, tablets, smartphones or any other device with a screen.
How many of these hours are at night time?
In the space of a few decades, relaxing or working in front of a screen at night time has become ubiquitous: we all do it. In the past, televisions were the size of your laptop, now they take up a whole wall, and it was only a few years ago that you had to read with a light on and even checking your emails was something done during daylight work hours. Nowadays, light is coming at you from all directions and at all hours, and it’s messing with your mind.
Light talks to your brain
Light entering your eyes triggers a hormonal response from within your brain. This is happens during the day in response to sunlight and at night time in response to artificial lights. Your brain has evolved to use these cues of light during the day and darkness at night to regulate our sleep – or diurnal – patterns.
In the same way that feeling hungry is the cue to eat something, the absence of light is the cue that it is time to sleep.
KEY POINT: The absence of light is the cue to sleep
Melatonin – the essential night chemical
During the day, sunlight triggers the pineal gland in your brain to produce the chemical serotonin. At night time, when the stimulation of light has gone, serotonin is converted into the chemical melatonin which makes you feel drowsy and tells you that it’s time to go to sleep.
Melatonin levels peak at different times throughout your lifetime. A teenager’s melatonin level peaks later than an adult’s, which is why they tend to stay up late and sleep in longer, but as we get older, the level peaks earlier and earlier. Ideally, this is reflected in an earlier sleep and waking time to suit your changing brain chemistry.
But melatonin does much more than just makes you drowsy. It is one of the most powerful antioxidants in your body and is particularly active in your brain and your mitochondria, an action which seems to slow down the ageing process at a cellular level.
KEY POINT: Melatonin is needed to sleep and slow down ageing
Why blue makes you blue
The screens of laptops, televisions, tablets and smart phones all emit a frequency of light which is blue. This is particularly disruptive to your brain because the sky also emits blue light (which is of course why we see it as blue).
At night time, when the light is meant to have disappeared so that your body knows that it’s time to go to sleep, the blue light from screens convinces your brain that it is still in fact daytime and it should stay awake.
This reduces the amount of melatonin that is released into the brain which reduces both the quality and duration of sleep. In fact, many people suffer from something which is akin to chronic jetlag where the body’s diurnal pattern is constantly out of balance.
The normal white light from light bulbs can disrupt some people but it’s the colour blue from screens which has the most profound effect on your brain chemistry and corresponding sleep.
KEY POINT:Blue light from screens reduces melatonin
How to tell if you’re got low melatonin levels:
– Difficulty falling asleep
– Difficulty staying sleep
– Unrefreshing sleep
– Lack of dreaming
– Increased appetite and reduced satiety
– Increased risk of some cancers including breast and prostate
– Reduced production of sex hormones
– PMS and menstrual irregularities
– Mood disorders such as anxiety and depression
How to minimise the effect of light on your brain
1) Turn off all screens at night time especially after 9pm.
2) Dim the lights around you at night time
3) Never check your phone or turn on lights if you wake during the night
4) Use a non-backlit reading device
5) Get adequate sun light during the day