We often hear two related facts:

  1. That using a lightbox can help maintain one's circadian rhythm.
  2. That using a computer late a night can make it harder to sleep at night due to the blue light emitted by the screen (monitor).

That got me wondering: Can using a computer early in the morning help maintain one's circadian rhythm, much like a lightbox?


1 Answer 1


I don't know if there is research on this, but if not, this might help.

Natural daylight contains a wide range of light frequencies - hence the rainbow, when it's split up. At different times of day, the light has to travel through a different distance in the atmosphere, which tends to absorb some frequencies, and scatter others. This is why the sky generally looks blue (blue and higher frequencies are scattered), but looks redder when the sun is rising or setting at the start or end of the day (absorption of blue and other higher frequency components).

Life on earth has adapted to this, so there are biological changes triggered by the regular cycle of more, then less, of the higher (" blue") frequencies. In simple terms, these changes include triggering of changes within the brain that hint to come awake, or feel drowsy, by working on the parts of the brain that control general arousal. The body has its own internal clock for these, but it also "syncs" to natural daylight, which helps to keep it on track. The triggering is apparently specific on frequencies at the blue end of the spectrum (not on red or other frequencies, or their relative proportions), as far as I have seen it discussed.

So this is the clinical basis behind the advice to avoid blueish light at, or towards, bedtime. Computer screens are also closely connected to mental activity and stimulation, which is a second reason why they aren't too good when heading for a sleepy state of mind.

Now, computer screens are not lit like natural daylight. They don't have a full spectrum - that's an optical illusion. Instead they usually have LEDs in three colours - red, green and blue - and they make all other colours by lighting these to different extents. Apparently the blue frequencies used to make various colours (including white) are close enough to the blue that's triggery in daylight, to have a similar effect.

At this point I have to start making intelligent guesses. What this means in theory is that yes, a computer or smartphone screen could act as a good lightbox in the way you're thinking, simply because it's capable of producing and avoiding blue light of the kind the body's clock is sensitive to. In fact there are a number of apps on smartphones which modify the displayed colours on the screen, to reduce the blue LED component. They make the screen look warmer and redder, or less brilliant white, but in fact they're doing it by selectively reducing the levels of all blue pixels.

So you could in principle create an app that (say) lit your screen a dim red at 6am, and gradually raised the general brightness and brought in the green and blue pixels over the space of say 15 - 30 minutes to reach full brightness. If the blue frequencies are close enough to those recognised by the body clock, it should work pretty much like a lightbox does.

Whether you want that, or want to leave a computer on overnight, or can figure a way to auto-switch on and auto-log in and run the app a while before waking, is a personal choice, though. Also the type of monitor might matter - some monitors have very low visibility off-axis (when not pointing directly at you), which means you are counting largely on reflected light, that may have a considerable filtering/muting effect. ("TN" displays are often like this, and "IPS" displays often have very wide viewing angles within which colours are faithfully seen). A monitor can also have poor colour range, or very low brightness. So it depends on the monitor.

Also bear in mind the noise itself might wake you up too:)

  • 1
    This is a fairly good answer. Can you please provide links to scientific articles or websites, and maybe reference some books, all of which can back up what you have said and provide further reading? That would then turn your answer into a great one. Sep 16, 2018 at 6:11
  • The obvious stuff is very copiously documented (Google/Wikipedia, it's everywhere), and as I've said, the deduced part probably isn't rigorously studied at all, so reliable papers won't exist. I posted this to give the OP the nearest to an answer they might get, as opposed to nothing... What kinds of links did you have in mind, apart from Wikipedia links dotted around?
    – Stilez
    Sep 16, 2018 at 8:47
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    I am not necessarily talking about your intelligent guesses, although some background links to this will help hence the reason for citations elsewhere. Peppering your answer with just Wikipedia links may not be the best course of action either unless there is nothing else. To help to start with, Light, Sleep and Circadian Rhythms by Dijk and Archer would be good to cite when talking about light affecting alertness and drowsiness. Sep 16, 2018 at 10:15
  • You're ahead of me. I know the info from general reading and knowledge, but I don't have a clue as to which are decent sources to cite (or any sources). If I added any, I'd just be googling them as I don't have a clue, and might pick poor sources as easily as good ones (I've never even heard of the book you mention, or either of its authors, for example). I don't feel comfortable trying to second guess good sources here, although if others add them, that would be good.
    – Stilez
    Sep 16, 2018 at 18:08

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