F.lux for biphasic sleep?



  • I am looking to change sleep patterns to 4am-8pm and 4pm to 8pm. Is there any way to optimise f.lux for this, or should I just turn it off?


  • f.lux team

    Assuming you mean 4AM - 8AM:

    While we know about 12-hour bifurcation in mice (Gorman et al UCSD), nobody knows a protocol to do true circadian bifurcation in humans yet. Instead, humans usually experience a longer sleep bout at night, and anything else is technically napping (there is a dip 12 hours later that makes this easier to do). But the research usually shows that napping is not as good for you as sleeping at night.

    Usually our advice for everyone is to spend enough time in darkness at night (>8 hours), because you cannot make significant amounts of melatonin during the day (no matter when you sleep) - and melatonin can fight cancer and inflammation. This is different than when you sleep, it's just that your body has one 24 hour rhythm--it's baked into your genes.

    If you're a night owl and you can't fall asleep until 4AM, minimizing light at night, and seeing more light during the morning is a good strategy - putting more of your sleep into the nighttime and shortening the nap is a good idea.

    If for other reasons (e.g., working hours) you do want to stay up until 4AM and you can't do it with the lights down, yes, turning off f.lux would be one way to do it. But for most people we'd recommend trying to put more of your sleep into the nighttime.



  • This looks like a feature request to define custom schedules for f.lux. What if I can't sleep for longer than 4 hours because of back pain? That would certainly be a valid reason to try a biphasic schedule.


  • f.lux team

    Well from a health/biology perspective, seeing too much light at night is just bad for everyone, regardless of sleeping schedule.

    People have taken their intuition about what light is doing (and how it works) and called it science, but there is real science about it, and if you're interested I do love to try to explain it.

    There is a difference between "light wakes me up" which we call the "alerting effects of light" and healthy circadian entrainment, which is much more about the pattern of light and dark throughout 24 hours. The second thing is harder to "feel" but it is probably more important for overall health.

    People seem to "get" the alerting effects (you can feel that bright light wakes you up), but with f.lux, we are concerned that modern society is basically ignoring the latter, and using light like caffeine at all hours. By seeing light late into the nighttime hours, they're squashing an important rhythm in the body that drives the timing of every system, so it matters for immunity, insulin resistance, heart health, etc. And of course, sleep also suffers when the circadian system is misaligned.

    Our view is that everyone should spend time in a consolidated period of darkness for at least 8 hours every day (hopefully more), even if you only sleep for a few of those hours. This is basically the point of f.lux as a product. People in ancestral societies spent 14 hours in the dark in the winter, and they didn't sleep the whole time.

    On the other hand, it may help a bit to reduce bright light before an afternoon nap, so we could indeed add a cue there to help. But it's probably more important to seek out a dark room, because during the day when the sun is up, the screen probably isn't the brightest thing you see.

    Love to hear your thoughts (and if my perception of how people are thinking about this is accurate).



  • Interesting, and fair enough.