Using laptops and tablets in the evening may disrupt sleep by suppressing melatonin secretion

I am a big fan of natural sunlight, and evidence links it with a range of potential benefits for the body. Light also has the capacity to effect the brain. The role for light here becomes immediately apparent in the winter, when light can be in short supply and some people find their mood and energy levels taking a distinct turn for the worse. In such individuals, some ‘light therapy’ can help energise and revitalise those prone to ‘winter blues’ and ‘seasonal affective disorder’.

It’s great that light can energise people in this way, but this is not something we want if we’re looking to get to sleep. One effect of light is to suppress the secretion of melatonin – the brain chemical that is integral to our sleep patterns. In January of last year I wrote a blog post about research which found that exposure to indoor lighting in the evening suppressed melatonin secretion. For those wanting to get the best sleep, I suggested turning the lights down low in the evening.

However, room lighting is not the only source of lighting in the home. Many of us are now surrounded by light-emitting devices such as laptops, iPads and tablets that could, in theory at least, disrupt our sleep at least in part through some melatonin-suppressing action.

A study recently published in the journal Applied Ergonomics looked at this issue [1]. Individuals were tested at separate times in 3 different settings:

  1. exposure to light-emitting device set at the highest brightness
  2. exposure to light-emitting device plus additional blue light (blue light is thought to be the most disruptive to melatonin secretion) exposure from goggles
  3. exposure to light-emitting device while wearing orange-tinted goggles that block blue light

Compared to no light exposure, there was significant suppression of melatonin secretion after 2 hours of light exposure from the device, and after just 1 hour of exposure to the light from the device and additional blue light from the goggles.

The tendency to be affected by this sort of light exposure will vary from person to person and even time to time, no doubt. However, for those that sense they don’t sleep that well, it might be a good idea to be mindful of the potential impact of light on melatonin. Some things worth thinking about include:

  • avoiding use of such devices within an hour or two of bedtime
  • limiting the time these devices are used for in the evening
  • getting a pair of blue-light-blocking (orange) sunglasses


1. Wood B, et al. Light levels and duration determines the impact of self-luminous tablets on melatonin suppression. Applied Ergonomics 29 July 2012 [epub ahead of print]

10 Responses to Using laptops and tablets in the evening may disrupt sleep by suppressing melatonin secretion

  1. Martin 6 September 2012 at 9:08 pm #

    There is actually a software that was written exactly for this problem:

    This little tool changes the screen’s color temperature according to the local day/night cycle. I’ve been using it for over a year now and it is fantastic. Also, it’s absolutely free. (I am not affiliated with this in any way)

  2. Robert 7 September 2012 at 1:26 am #

    Dr. Briffa, I’d like to mention that there is a free app out there ( that will adjust the light output of your pc or laptop to minimize the effect on melatonin production in the evening. You set it based on your zip code, and it changes the balance of light based on the time of day. (You can also manually set the light output on your TV toward the same end.)

  3. PhilT 7 September 2012 at 2:09 am #

    The free Linux operating system has cottoned on to this there’s a program called Redshift which changes the colour temperature of the monitor according to the sun’s position / time of day in your locality.

  4. Seppo 7 September 2012 at 4:48 am #

    There’s a software that can, at least partially, fix this. It adjusts the color of your computer monitor depending on the time of the day. In the evening it shifts the color spectrum towards yellow and orange and away from blue.

    It’s available for free from here:

  5. Jean 7 September 2012 at 8:25 pm #

    F.lux – Fabulous, it ‘soothes’ your eyes if you wear contact lenses too!
    I noticed a difference almost immediately.

  6. Kay Nelson 7 September 2012 at 10:00 pm #

    Flux works for me too Both on my PC and Mac laptop and on my tablet and kindle app it’s possible to soften the lighting in the evening. Flux is well worth trying.

  7. mamaprophet 8 September 2012 at 12:19 am #

    Kay that’s good to know as I was having difficulty getting to sleep afer using my Kindle. Thanks.

  8. Heather 8 September 2012 at 12:25 am #

    Another F.lux fan here. I have to use my computer until just before bedtime but this has made a huge difference.

  9. William L. Wilson, M.D. 9 September 2012 at 12:11 am #

    John–great post. Anything that interferes with melatonin has the potential to interrupt sleep. That includes diet. Our modern diet of processed foods containing sugar, HFCS and high glycemic carbohydrates especially from grains seems to be bad for our brain. Over time these dietary elements can lead to diffuse brain dysfunction that we now call Carbohydrate Associated Reversible Brain syndrome or CARB syndrome. People with CARB syndrome develop symptoms reflecting low levels of monoamine neurotransmitters like serotonin. If you have low levels of serotonin in your brain, you will also have low levels of melatonin because melatonin comes from serotonin. If you want a good night’s sleep, stay away from the junk!

  10. Joe 12 December 2012 at 12:12 am #

    Be careful with F.lux, I tried it and kept on getting headaches

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