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Blue Light & Sleep




We keep hearing about how our devices can affect our sleep. At Rest Space we've dug into the research to paint a picture of why they are affecting our sleep and what we can do to manage it. Imagine if we didn’t have artificial light in our modern society; how would we stay out later when it gets dark? How could we get those extra hours of work in or have that feeling of safety and comfort? As with most good things there is a catch; artificial light has an impact on our sleep.


If you find that when you’re lying in bed scrolling on your devices and struggling to sleep, the issue may be closer than you think. The light emitted from our laptops and tablets can disrupt our sleep and the quantity of sleep by up to a few hours. This can lead to your sleeping patterns changing or feeling a little more groggy in the morning from reduced hours of sleep.


In recent years, with the rise of personal devices there has also been discussions around whether it can affect your body clock and in turn your sleeping patterns. Blue light isn’t all bad for you; it is very beneficial for us during the day. It gives us that energised feeling in the morning when you wake up and it has been seen to boost our attention, reaction times, and mood. We will look at what the research says and suggestions to minimise the impact of blue light on our sleep.


The Science behind blue light


To start off, the light that we can see and process with our eyes is called Visible Light (380nm to 700nm). A part of this visible light is blue light (450nm to 485nm, which has been seen to have the most powerful effect on your sleep-wake internal body clock or in another word, your circadian rhythm. The light from your devices often appears white. But they can give off wavelengths in the range of 400nm to 490nm, which is blue light. 


When you look at lights of these wavelengths, it suppresses your melatonin (the hormone which can help you fall asleep). Although certain wavelengths of light can do this, Brainard et al. (2001) found that melatonin suppression was best seen in the blue light spectrum between 446nm to 477nm.


It is helpful to note that Cajochen et al. (2006) found that green light at 550nm did not suppress melatonin.


So how long do you have to be exposed to blue light to affect your sleep then? Thapan et al. (2001) found that after 30 minutes of light exposure, melatonin production was fully suppressed. Though it was not found to cause a long-term impact on your melatonin, they did find that it took approximately an hour for the melatonin to return to its normal level. 


In addition, as we get older, we produce less melatonin and light is less effective at suppressing melatonin. But research has seen that light-induced phase advance of melatonin circadian rhythm is not impaired with age.The circadian rhythm was found to respond to both morning and evening light exposure (blue-enriched or blue-depleted) without significant differences between morning-types and evening-types of persons.


What does this mean for you?


The light from your devices often appears white. But they can give off wavelengths in the range of 400nm to 490nm, which is blue light. In combination with things on our devices that could be perceived as more important than sleep or FOMO, this could delay our sleep by up to a few hours.


The simplest way of managing this is putting your devices away one hour before you plan to sleep. Nagai et al. (2019) has seen that a suppression of blue light at night effectively maintains circadian rhythms and metabolism.


Some other ways that you could try out are:

  • Cutting back on devices a few hours before bed

  • Use a dim red light bulb as a nightlight

  • Exposing yourself to more bright natural lights in the day 

Research is pretty definitive that a dark room is the best room to sleep in and the effects of blue light on sleep. Combine this with a cool room and roughly the same sleep and wake time to get the best quality rest!



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