How does blue light affect sleep?

If you've been reading up on the effects of excessive screen time on one's health, chances are that you may have come across the term �blue light� more than a couple of times. This form of light has been found to have a disruptive effect on our sleep. While it may seem hard to believe, the verdict (and science) is out on the exact relationship shared between blue light and sleep quality.
Photo: Active Health

The effects of blue light on sleep

Blue light is essentially light of a particular wave length out of the entire spectrum of light. This means digital devices are not the only source of blue light as it can occur naturally as well (with sunlight for example). However, artificial light sources such as those from digital devices and fluorescent light bulbs have been found to be more concentrated in blue light than any other sources. What exactly is so special about blue light that makes it so disruptive to sleep?

� Effects on melatonin production

Blue light has such a profound impact on your sleep simply because it directly affects your body's production of the sleep hormone melatonin. So how does blue light affect this important sleep hormone? Melatonin is responsible for making you feel sleepy, and blue light suppresses the production of this important hormone. This is why sunlight wakes you up naturally in the morning and you tend to feel sleepier in dark environments. Even though your digital screens are such a small light source compared to natural sunlight, it still has significant effects on your sleep cycle. This is because your brain perceives blue light through the melanopsin receptors behind your retina, so all the blue light from your devices (and lots of it to boot) get an all-access pass to your brain.

� Effects on circadian rhythm

Blue light�s role in maintaining melatonin levels in your body makes it a huge factor in controlling your body�s circadian rhythm. Your circadian rhythm is responsible for telling your body when it�s time to sleep and wake up, so any disturbances to this cycle will have an effect on your sleep. As a result, you may experience difficulty falling asleep or even staying asleep.

In short, blue light interferes with your sleep in two ways � first by disrupting your body�s production of sleep-inducing hormones, and second by throwing your body�s natural circadian rhythm off-balance. By negatively affecting the quality of our sleep, blue light exposure can prove to be really detrimental to our health. Apart from sleep-related issues, there are two other negative side effects of blue light exposure that are just as worrying.

Other consequences of blue light exposure

1. Digital eye strain

We get a lot of blue light exposure via our digital devices and this can lead to strained eyes, where our eyes feel sore and dry and our vision becomes less clear. Along with the physical aches associated with spending long hours in front of a digital screen, this can lead to a lot of physical discomfort.

2. Increased risk of macular degeneration

The consequences of blue light exposure go beyond just a mere eye irritation and can even lead to serious vision-related problems. Prolonged exposure to blue light over time can cause cell damage in our retina and make us more susceptible to macular degeneration, a problem that may lead to a permanent loss of vision.

Photo: Active Health

5 ways to minimise your blue light exposure

1. Put your devices away at least two hours before bedtime

Since the blue light emitted by your digital devices will affect your sleep, the easiest solution to the problem is to stop using your devices in the hours leading up to your bedtime. The less screen time you engage in, the better. However, if going device-free is honestly impractical, don�t worry: studies have found that you can continue using your devices up to two hours before bedtime, after which your melatonin production will be affected. It may be hard to abstain from your favourite devices, but two hours is a reasonable target to aim for!

2. Adjust your screen brightness and turn on night light filters

The simple act of lowering your screen brightness can play a significant part in reducing your blue light exposure. Lowered screen brightness means less blue light, so your melatonin levels won't be disrupted as much. Turning on your night-light filters will kick the protection up a notch � the light on night modes are of longer wave lengths, making them less harmful to our melatonin production. You can even download special light altering filters that will change the blue light into orange or red light, both of which have less melatonin-blocking effects.

3. Use devices with smaller screens

The amount of blue light you expose yourself is proportional to the size of your device's screen and the distance between said screen and your eyes. You can easily minimise your blue light exposure by using devices with a smaller screen (such as a smartphone instead of a laptop) and viewing the screen from a further distance.

4. Change your home lights to warm lights or �smart� lights

Apart from changing the way you use your digital devices, you can also modify the lights at home to make them more sleep-friendly. Warm lights don�t affect melatonin levels the way bright lights do, so get some night lamps with warm lights or invest in �smart� lights that automatically switch to warmer shades at night.

5. Get protective eye wear

If your lifestyle causes you to be frequently exposed to blue light, investing in a pair of blue light-blocking glasses for the times you spend looking at a screen can be a good compromise. You can also try looking out for lenses with anti-reflective coatings � these can block blue light exposure as well.

Apart from minimising your blue light exposure, you can also consider resetting your circadian rhythm by ensuring that most of your blue light exposure is done during the day. There are two easy ways to do this.

Resetting your circadian rhythm

1. Get more sunlight during the day

Getting more blue light during the day allows your body to get used to the light, so that at night when you decrease your blue light exposure, your body will recognise that it�s time to sleep. Going out in the sun will do you lots of good in other ways too, as getting some exercise outdoors can help you to sleep better. Simple activities like jogging or cycling work perfectly well and you don�t need to invest long hours in exercising � just speak to any expert at our Active Health Labs for a simple exercise plan!

2. Use a light box

If your circadian rhythm is completely haywire as a result of heavy shift work or constant travelling through different time zones, you can reset it by using a light box. This form of light treatment is known as photo-therapy and it involves exposing yourself to blue light of a strong intensity for 30 minutes in the morning. By doing this (along with staying away from blue light at night), you can restore even the most irregular of circadian rhythms.

Photo: Active Health

Benefits of blue light

Since we are on the topic of getting more blue light during the day, it�s a good time to raise the point that blue light does have its benefits too. Yes � exposure to blue light at night can disrupt your sleep and too much blue light is indeed bad for your eyes, but there are ways in which blue light can be beneficial too.

1. Mental boost

Blue light is stimulative by nature and can help to boost your alertness, improve your mood and fire up your memory.

2. Eye health

Exposure to certain levels of sunlight is essential for maintaining health eyes and eyesight in children. In fact, a study by the University of Sydney found that children who went out in the sun more often were less likely to develop myopia.

3. Regulate circadian rhythm

Limiting blue light at night helps your circadian rhythm but getting zero blue light throughout the day won�t exactly do you any good. As mentioned previously, exposing yourself to blue light during daylight hours contributes to a healthy circadian rhythm and will help you sleep better at night!

Blue light may get a negative reputation when it comes to sleep quality and eye health, but it isn�t necessary to avoid blue light totally � you only need to minimise your blue light exposure at night. Maintaining a healthy sleep cycle is all about striking a balance between getting enough sunlight during the day and staying away from artificial light at night. Once you get into the rhythm of things, you are bound to notice the difference!

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