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Light-Emitting Screens Before Bed Disturb Sleep

If you have an e-reader or tablet, the chances are that you use it right up to going to bed. Whilst such devices have their obvious advantages, new research suggests that you could be better off sticking with your traditional paperback book.

The study published in the Proceedings of the National Academy of Sciences found that participants using iPads displayed reduced levels of the sleep-promoting hormone melatonin. They also took longer to fall asleep, and spent less time in rapid-eye movement (REM) sleep. Furthermore, they also reported feeling less sleepy in the evening but more sleepy the following morning.

The problem with blue light technology.

This study joins a growing body of evidence highlighting the potentially detrimental effects of light-emitting technology on our sleep and long term health. When you look at human physiology it is quite simple to understand why such devices are causing us so much trouble. Humans have evolved to live on a planet that cycles between light and dark over a 24 hour period and so consequently has become tuned to the rise and fall of the sun. It achieves this by light-sensitive cells in our eyes detecting the changes in light and informing our internal body clock.

Your body clock could be described as the most advanced timer switch ever created. Highly accurate, it triggers the timely release of thousands of chemicals throughout the body helping us to wake up, exercise, eat, and then sleep. Our very existence hinges on its regularity, with dysregulation now linked to obesity, diabetes, cancer, heart disease, poor mental health, and of course sleeping issues.

So why are modern electronic devices proving to be such a problem?

Over the past decade we have seen the arrival of a new wave of light-emitting gadgets into our lives such as smart phones, LCD TVs, e-readers, tablets and laptops. The main issue with them is that they all emit a type of light called ‘Blue Light”, so called because it is the same wavelength as a blue sky – which is exactly where the problem lies. By looking at such a device before going to bed, you can confuse the brain into thinking that it is morning, thus knocking your body clock completely out of sync.

How big is this problem?

A recent survey by the National Sleep Foundation found that nearly 90 percent of adults and 75 percent of children reported having at least one electronic device in their bedrooms, and many reporting having multiple devices, such as televisions, laptops and tablets. The reality is that it is now commonplace for such devices to be part of our bedrooms and bedtime routines. Scientists are most worried about the impact such devices are having on the sleep of children and young adults because, up until the age of 19 years for females and 21 years for males, this is when the bulk of brain development occurs. Without adequate sleep, the brain is simply not given the time to grow physically, emotionally or academically.

What can you do to limit the impact of blue light on my sleep?

The easiest and most obvious way is to make an active choice to darken down your evenings by avoiding such light-emitting technology. Switching off all your devices and dimming the lights 40 minutes before bed will help tell your body clock that it’s time to sleep. If you really need to use such devices then installing f.lux can be helpful – it’s a programme that adapts the colour of your display screen to the time of day: warm at night and like sunlight during the day. Investing in a traditional alarm clock and leaving your phone in another room will also help. If you like reading in bed, then I suggest you go for a good old fashioned paperback book with a small bedside lamp.