How important is it to not be exposed to significant amounts of blue light in the earlier part of the evening, 6h-3h before you go to bed?

  • I work infront a computer screen from 18.00 until 00.00 five days per week. Having trouble falling asleep at night and feeling a bit jet lagged has always been a part of doing this job for me.

    Before I knew about the effects of blue light on the circadian rhythm I used to blame the problems on being too active late at night and not getting enough time to wind down. This caused me to set strict times for when I wanted to go to bed at night (03.00) and rise in the morning (11.00). I kept having problem falling asleep at night, even though I had given myself a generous amount of time to relax after work. I figured that if I just kept rising at 11.00 it would straighten things out, but it never really did

    Since I learned about the effects of blue light on the circadian rhythm, the time between 00.00 and 03.00 has been spent in a very proper light environment. The new rutins have been very relaxing and I think they might have helped a little bit, but they have not solved the problem

    When I dont work for a week or more I have no problem falling a sleep at night. During this time I usually go to sleep 01-02 and rise 09-10 since it fits better with the people around me.

    Either there are other things than exposure to stimulating light that is hindering me from keeping a stable sleep schedule while working or I get the stimulation earlier in the evening. What do you guys think?

    /Mikael N

  • There are two ways to adjust your timing: light in the morning, and less light at night. Since you are a night owl, you may not be able to do the whole thing with "less light at night" and may need to see more light during the day.

    My main question is: what is the difference between your days off and your work days? On the days you don't work, are you spending more time outside? Or is the only difference the time on the computer?

    The easy thing to try is to spend some more time outdoors (or in brighter light) just after you wake up.

    Still, your "midnight" lighting and computer screen could just be too bright, and they both may need more dimming before bed. So try as much as you can to make things dimmer a couple hours before you sleep.

  • In response to your "topic" question, most people need a balance of bright light throughout the day: light in the morning, and light in the early evening (it depends on season, but think of sunrise and sunset). Without both these signals, your clock will move earlier or later.

    So in the winter you'll probably be more sensitive to light at night, because relative to your day, it "looks" brighter to your body.

    The seasons teach us that we are really flexible, but we have to see enough light in the morning (in the daytime) as well as in the evening.

  • Thank you for your replies, herf

    I think I spend more time outside than most, both on work days and when I am free, but of cause more than average might still not be enough...

    I have read a lot of information about blue light and how it affects the circadian rhythm and since I dont really affect anybody els 00-03.00 I have been able to be pretty strict about not seeing alerting light these hours; Uvex glasses, dimmable rgb-lamps and flux. When I wake up I spend some time in a very bright room reading at the computer (five close windows in the suns direktion, 4x60w 6500k light and 6500k at the computer), about an hour after I wake up I go out for some errands or a walk.

    Sailing or fishing for a full day definitively puts me to sleep at night. I do these activities for a week straight a couple of times per year and sleep is always a non issue then. Granted that I also move around much more on these days which might further benefit the sleep(lack of physical exhaustion and alot of mental exhaustion late in the day was how I used to make sense of the delayed time of sleep before I knew about bright light)

    This leaves only the light exposure infront of the computer 18.00-00.00. I have flux installed and I have it on 4000k for the first 5 hours and then 2700k. The screen is 27 inch and I sit 50 cm away from it and stare at it intensely for the whole 6 hours. Maybe the close distans and the fact that I pay such close attention to it makes it a very strong bright light source.

    Is it obvious that your circadian rhythm would be delayed if you woke up 08.00, spent the day in a dim lit indoor environment, then starting 18.00 spent something like 2 hours in a super bright place and spent the last 4 hours in the dim lit indoor environment with Uvex glasses on?

  • Without dimming, f.lux at 2700K still makes a large stimulus on its own - here is a rough simulation of your 50cm use:!id=Thunderbolt 27/2700K-Thunderbolt27&distance=20

    We don't really know how the retina works at low light levels, but dimming seems to help.


  • Around 10 hours before your wake time, you are likely beginning the "delay" period of your PRC. There is a substantially larger effect 8, 7, 6 hours before, though.

  • I think a big part of the problem is not wearing yourself out during the earlier part of your day with exercise and other activities (like mental activities in addition to physical ones). The more physical and mental exercise you get during the day, the easier it will be to go to sleep at night and wake up like 5-7 hours later feeling refreshed and ready to do it again - especially if most of that exercise (or all of it) happens during the first half of your day. It can take a surprisingly long time for the body and mind to unwind! 3 hours is definitely not enough.

    So, getting plenty of general activity every day can help you have a consistent day/night schedule without much difficulty.

    Light exposure is still a big factor, but if you're not exercising during the day but instead are just sitting around all day, then you're not really going to be tired enough at night to go to sleep. I think I am living proof of this because I can easily stay awake for like 24-36 hours or more every single "day" if I don't really do anything while I'm awake. If I get a ton of physical exercise one day, then I have no problem going to sleep like 15-18 hours after I woke up. In fact, I'm almost desperate for sleep by then. :) Again though, if all I'm really doing is sitting all day, then I'm not really going to be tired at night and it could be well over 24 hours before I want to go to sleep.

    As embarrassing as it is to admit, I don't get any exercise. I literally sit at my computer the entire time I'm awake. With this lifestyle, I don't have a regular day/night schedule. I just go to sleep when I need to go to sleep, and I wake up when I can't sleep anymore. I don't desire a regular day/night schedule because I know it can't happen due to the fact that I'm not doing anything while I'm awake to make myself tired by the time I've been awake for like 15-18 hours - which is pretty much when an active person should go to sleep. Like, wake up at 6am, be active most of the day and then go to bed by 9 or 10 or 11 or even midnight at the latest.

    I think where the importance of light exposure comes in the most is, you want to make sure you're not suppressing melatonin production at the time of night when you want your body to start producing it, and you don't want to interrupt it once it has started because it can take a few hours for it to get going again. That way, you can go to sleep at night due to being kind of exhausted and get the quality of sleep that you need thanks to the melatonin (it's not just due to the melatonin, it's due to what happens when there's a sudden increase of melatonin in your system, but still).

    So, you could still probably fall asleep after being awake for like say 16 hours due to wearing yourself out during the day, but if you go to sleep without proper production of melatonin first, then you might not wake up 5-7 hours later feeling refreshed and ready to face another day. You might feel like going right back to sleep, or you might not even sleep a solid 5-7 hours.

    Of course, getting plenty of exposure to nice bright morning sunlight upon waking is quite critical as well. Actually, I kinda think it would be the MOST beneficial to wake up just before sunrise. Like, just as dawn is coming. Imagine going to sleep shortly after sunset and then waking up just before the first morning light can be seen before sunrise - and then letting the sunrise become a part of your morning routine. Look at how the birds do it: they go to sleep with the sunset and many of them are awake and chirping energetically even a couple of hours before sunrise! I live in Minnesota though, so I know that Winter is quite a different story. :)

    So yeah, we humans are designed to be active during the day, so it makes sense to have problems with sleep and/or with our circadian rhythm if we're mostly inactive all day (like me, sitting in front of my computer all day). I think it doesn't matter how perfect of a job you do with your light exposure while you're awake if you're inactive most of the day. You can't expect a rechargeable battery to need recharging if you're not really using it.

  • @TwoCables I've been watching a show about these guys catching tuna all day on a boat. They might lose a good bit of sleep here and there, but they're literally outside all day. Maybe small amounts of time eating in the cabin or getting ready. I think it'd be fun to try for a while.

  • @Tungsten_smooth said:

    @TwoCables I've been watching a show about these guys catching tuna all day on a boat. They might lose a good bit of sleep here and there, but they're literally outside all day. Maybe small amounts of time eating in the cabin or getting ready. I think it'd be fun to try for a while.

    I'm not so sure. They don't get to shower every day, and the job is actually very dangerous. If you're in Alaska, then it's even more miserable. Overall, it just sounds like a miserable job to me.

    I'd rather just go for long walks every day or something if I wanted to be outside. You know, like, almost live outside. Just, wake up, get dressed, and go outside and just walk around. Come home to eat when hungry, and go back outside to walk around some more. Come back home to eat again when hungry, and then stay home to unwind.

    If/when it's too cold (or even dangerously too hot and humid) to walk around outside, then yeah of course stay inside. Maybe buy a treadmill or something for those kinds of days.

    This is good advice for myself. Wow. lol :)

  • @TwoCables Well in contrast that sounds horribly boring. Maybe add in some social interaction just a bit etc. Chase down a bear, or, something that won't eat you.

  • @Tungsten_smooth said:

    @TwoCables Well in contrast that sounds horribly boring. Maybe add in some social interaction just a bit etc. Chase down a bear, or, something that won't eat you.

    You must be an adventure-seeker. Me, I get extremely crabby and unhappy when I'm working hard and sweating my ass off and I haven't showered in 3 days and I don't get much time to myself, etc. Being on one of those fishing boats just doesn't appeal to me one bit. Then you have the icy cold SALTwater spraying on you all day, you have a high risk of falling off the boat and DYING or having some other serious injury..... it just doesn't appeal to me. This job is known as being just about the world's most dangerous job.

    If I wanted to be outside a lot, then I'd much rather do something that's safer and isn't so damn difficult and unpleasant.

  • @TwoCables Alright yeah, but it's healthier than what most of us do all day. Hunting / fishing is fun though, and much safer.

  • @Tungsten_smooth said:

    @TwoCables Alright yeah, but it's healthier than what most of us do all day. Hunting / fishing is fun though, and much safer.

    Yeah it's healthier, but I admit that I'm not sure why you took it to that extreme of an extreme.

  • @TwoCables I thought it was entertaining to watch other people catch large fish, so I put it here.

  • thank you

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