Why is bedtime not taken into account while wake-up time is ?

  • Hi all,
    well I may not have understood everything but I am surprised that the time I go to sleep (say 10pm, 22:00) is not taken into account.
    If my bedtime is 9pm, I may want the bedtime light at 7pm or 8 pm to make sure I have no blue light before sleeping.
    Maybe I missed something but it doesn't seem possible with the latest version. Or is this useless ?
    Happy new year soon anyway, so bedtime will be late tonight !

  • @Gilles Oh, but it is! That's why they ask for your wake time. I'm sure @f-lux-team will do a whole lot better job of explaining it because they know a lot more about it then I do, so be patient for their feedback.

  • Hi Tungsten-smooth,
    An Happy new year 2017 !! Happy sleeping !
    well to me, wake up time is one thing and bedtime is another one.
    Let's take this 2 situataions:

    1. waking up at 7am and going to bed at 1pm
    2. waking up at 7am and going to bed at 10pm
      How does f.lux makes the difference if I want no blue light say 1-2 hours before bedtime ?

  • @Gilles I think what you're saying is: you believe that bright light keeps you from sleeping, and maybe you have work to do late at night? This is basically true (light makes you more alert), but only one of several ideas here. We usually think that the "circadian" idea is perhaps more important.

    The main idea with circadian timing is that bright and dark set your internal clock, and seeing "daylight" 7 hours before you wake up would usually push someone's internal clock later, so they would want to stay up even later the next night, and they'd be very groggy in the morning. So even if you are sleeping less than 8 hours, you'd want your circadian clock to be close to someone who is sleeping more.

    There is some additional evidence that the total melatonin your body releases in a night (apart from sleep) may help with things like fighting off cancer, so there are some important long-term reasons to allow your body a longer period of "darkness" at night, even if you don't have the chance to sleep as much.

    And while we do know that this isn't true all the time (love to hear your view), it's important to note that only about 1% of the population can perform as well on 6 hours of sleep as 7 hours, so we have not wanted to encourage this view that everyone can be a super-human short sleeper (some people promote this idea, but it is not right). For 99% of the population, a week of "6 hour" sleeping can make your driving performance as bad as someone who's legally drunk, and you won't really notice that this is going on. So I guess we are promoting what is best for "most people" and it might not be best for your schedule, a deadline, etc.

    We have a "disable" feature for people who need to work late for one night, but if there is one goal in the software, the idea is that you want to set your internal clock to a time where you don't feel groggy the next morning, and we're still learning more about what's best for each person. Lots more to do.

  • @herf
    Well, no! I think what Gilles wants is what I want too: a setting that lets me tell f.lux my normal day-time activity span. For me it runs from 07:30 to 23:30. Each day. 8 hours of sleep.
    f.lux as it is almost forced me to bed earlier.
    I have several friends who need much less sleep: one of them has never slept more than 4 hours a day. he is now in his 80s and still going strong.
    So maybe 95% of the population does not need an f.lux setting for their day-time activity span, but certainly I and my wife and my friends do.

    So, until f.lux provides such a setting, it is quasi useless to me.

  • @herf - Make that three people (at least) who want independant bedtime and arise-time settings. For whatever reason, I get up (naturally) between 5 and 6 AM. However I may go to bed any time from 1 to 4 AM (my average in-bed time is around 2.5 hours); I keep track/records with my FitBit. I do nap during the day and evening.
    I find that f.lux has helped me transfer at least some of my evening nap time to actual bed time. (I can go to bed a little earlier than I used to without tossing and turning for several hours.) I firmly believe that one should not practise staying awake in bed (no TV; no reading), so if I can't sleep, I'm likely to get up for a while.
    BTW, independant bedtime and rise time would also help those folks with the opposite "problem" - that they need more than 8 hours of sleep.

  • @pwmeek - :-) you sound like Winston Churchill: naps during the day… My wife and I both have a nap after lunch, but given our age that is not uncommon. We used to read a little in bed before falling asleep, but now our consumption of text comes mainly from the web, so it's yet more screen watching, for which f.lux was designed.
    I usually have no problem falling asleep, even on airplanes, trains, buses. But if I do, I tend to think of some difficult problem, from mathematics or computing, and that usually sends me off quickly.
    I used to fly around the world a lot (literally) and then melatonin pills, if strong enough, did help, especially in the west-to-east direction.
    And yes, being able to set the bedtime, or the usual span of being awake, would also help those who need more sleep.
    I do however agree that an app like f.lux should not be used routinely to try to stretch one's up-time.
    Still, we have at least four people (you, Gilles, my wife and I) who want two parameters: wake time and period of wakefullness (or bedtime).


    PS 1: I did once leave Geneva on Sunday evening, flew to Frankfurt, then Singapore, then Sydney. Meetings there, then on to Los Angeles, missing a day going over the date line, another set of meetings in San Francisco, then Chicago and Boston, which also gave me two consecutive nights spent on a plane instead of a room with a shower, finally London (where I did get a shower) and then back in Geneva on Saturday morning. Northern and Southern hemisphere, date line, winter and summer. Not to be recommended.

    PS 2: noticing that it is probably not too difficult to set the display's colour temperature from the command line, I may yet attempt to write an app myself with LiveCode.

  • Reading this with some interest, because we have said for a while that older people need very different schedules than younger ones. We have some improvements coming in this area in the future.

    Still, I am curious how you are thinking about the color change exactly - if I can ask one question: what do you think the screen changing does to your body? Or how do you experience it?

    Here's how we've designed it:

    We intend for you to have a sufficient "dark period" in your day, no matter what your sleep habits, but we're trying to synchronize overall with the timing of your sleep.

    First, the common sense reason: it takes your body some time to calm down from the immediate effects of seeing brighter light (an hour is a good estimate for this). But of course the timing we use doesn't make much sense if you are sleeping much less than 7 hours.

    The second reason is that it is hard to find many places on the earth where you have >16 hours of bright light (except for a few days of the year in very northerly regions). And so we think (and we have models that say this) that seeing many many hours of bright light will mess up your circadian timing (making it harder to feel tired at the right time, and leading to worse sleep at night).

    This second reason may not make any sense to a person who naps 3 hours a day and only sleeps 3 hours at night (why would you then need 5 hours of darkness in addition?). But it's clear that the body still has ONE major rhythm - body temperature is still adjusting to the 24 hour day, and hopefully melatonin is as well in that interval. And also, the strength of these rhythms has important implications for overall health. So even if you are sleeping less at night and napping during the day, encouraging this rhythm (we think) can have very positive health benefits. This is actually our main focus recently, but it is hard to communicate succinctly.

    So in this second mode, we are not signaling "be active" or "be asleep" but we hope to signal to the body "it's the daytime" and "it's the night" - which, biologically is a rhythm that is hard to compress. In the winter in nature, for instance, a 14 hour night would not be telling you "sleep 14 hours", if the analogy makes sense. But in the winter your body would produce more melatonin, and it's possible that you'd have better resistance to common colds and even cancer like this.

    Related to this: in times past, people seem to have experienced "segmented" sleep throughout the dark period, so reading up on this topic can explain a little bit how we're thinking about a "dark" period at night.


  • @herf several questions, so several replies:

    — the colour change makes me sleepy, but I will have to use the app for longer to give a more definite answer.

    "We intend for you to have a sufficient "dark period" in your day, no matter what your sleep habits, …"
    Perhaps, but who are you to decide what "sufficient" is for me? People are quite different. I've never needed more than 8 hours. I do get tired if for longer periods I get less sleep. But I get restless if circumstances don't allow activity for an average of 16 hours a day. For example, I can't stand beach holidays, lazing in the sun. This is the same for my 4-hour-sleep friend: he needs 20 hours of activity or he gets bored or restless. So I definitely want to be able to set my length of time.

    — It does take time to "calm down", but on a normal day that would, for me, be around half an hour at most. Some other members of the family need an hour. They also need an hour to wake up. I wake up instantly. In fact, I can get up at a certain time, without needing an alarm clock. The precision has gone down somewhat over the last decade, but it used to be less than five minutes from the desired time. I'm then fully awake. No drowsy period. I realise I'm lucky, but I am certainly far from alone.

    — What most disturbs my sleep is worries and upset. I cope with those by long-term planning, prioritising, and keeping good relationships. Not always easy of course.

    — Yes, there is one major rythm (in the large majority of people, there may be some pathological cases, I would not know), and it's regulated by more than one hormone. But I was under the impression it was 25 hours, with the melatonin coming in to adjust it to 24 hours.

    — Studying the habits of Finns, Swedes and Norwegians, and Sami people would be interesting, though such studies have been made I'm sure. There is no equivalent in the Southern hemisphere, even Tierra del Fuego is not further South than Edinburgh is North. My Finnish friend told me once that the warming climate has made suicide rates go up: there is less snow cover during winter, reflecting less light, making the already short days much gloomier (I take him on his word, I did not check statistics). However, I did travel higher North than Rovaniemi, and it's not just a few days that the sun is out all the time. It's out for weeks. It was also quite a hot summer during that trip.

    — In times past the habits during winter and summer changed a lot indeed. Where I live, 46º North, there is sunshine in summer until very late, 22:00, and the birds start singing already at 04:00 when it gets up again. Inverse in winter: down at 16:00 and up after 08:00. We keep our rythm largely through the clock, i.e. physical activity, not really the daylight. Rummage on the fields in summer evenings, make clocks in winter evenings. In addition, our area here has long periods of overcast sky when the daylight intensity is low all along.

    — All that said, it is important to sleep well and to sleep enough. How a particular individual does that is up to them; apps can be of help. One's mental peace is a big factor, so is diet (*), habits, etc.

    All in all an interesting topic.
    Et ceterum censeo tempus somni determinandum est (if my Latin is still worth anything)


    (*) from some reading I suspect that the inordinate amounts of sugar in today's prepared foodstuffs is at least partially to blame for insomnia and hyperactivity.

  • Thanks for the reply - so I would summarize by saying you are mostly using f.lux as a cue to adjust how alerting the display is right before bed, and not to "shift" your circadian timing.

    We think probably 20-50% of the population needs some "phase shift" adjustment (meaning you would want f.lux doing something more aggressive to the light you see), and some of those people need this only at certain times of the year. Some people are just close enough to 24 hours that the only thing we can do is exactly what you describe: tell them it's bedtime and get them off the internet. :)

    For the others, the big trends are that younger people (in their 20s) often have very "long" internal clocks and require a bigger push to earlier timing, and some people later in life have a "short" clock that makes them wake up too early. Also with age, we know that the sleep drive can be somewhat lower, so people have more interrupted sleep.

    And yes, the body's clock is now thought to be just slightly longer than 24h for most people (about 24.2) - the 25 hour number was for people in constant light, which is not what most people do.

    But we think (basically for anyone) maintaining the "right" light-dark cycle (more light during the day and less at night) will improve your ability to fall asleep and your ability to sleep through the night, but we have a ways to go to show that this helps every kind of person and not just some.

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