Use F.lux To Sleep Better After Late-Night Computer Activities

flux   Use F.lux To Sleep Better After Late Night Computer ActivitiesA couple of months ago, Varun wrote about a very interesting yet controversial application. Since then, a lot has been learnt and the app has come quite a long way. I’ll attempt to review the app again but this time, I’m testing the Mac version and I’ll try to look to it from a totally different perspective from he did. First, let me start off with a little background.

You must be familiar with modern LCD screens, right? If you look carefully, most of them have a button to automatically change the attributes of the screen to adjust for the types of media which is being viewed: one specially tweaked for movies, another for photos, a separate one for text and there’s one we’re particularly interested about — night.

You see, working in front of a computer screen at night raises a particular concern. The fact that you’re staring at a bright screen late at night when your body is supposed to be turning in, disrupts your circadian rhythm. A bit of medical jargon coming your way — during nighttime, darkness permits the production of melatonin by the pineal gland. Melatonin causes drowsiness and in tandem with the central nervous system, controls the circadian rhythm. In layman’s term, all this means is the bright light from the LCD screen screws up your sleep-wake cycle.

That’s why there’s a customized “Night” setting on your LCD. Furthermore, there are several apps that will reduce the brightness of your screen while working at night; Shades is one example of a Mac app that will do just that. I don’t know if you’ve noticed the LCD’s reflection off a person’s face at night — it’s mostly bluish white. Technically, the specific colour temperature is 6500K; also known as daylight. That’s right. If you find it hard to fall asleep after using your computer, this is why.

F.lux addresses this issue but it does it slightly differently. Instead of reducing brightness per se, it actually warms the colours you see on your screen and imitates the lighting in the room during nighttime. It’s quite hard to wrap your head around until you actually use it but I’ll do my best to try and explain it.

After downloading and launching the app, it will ask you for your location and the type of lighting that’s in the room — tungsten, halogen, fluorescent or daylight. Based on the information, it calculates exactly when the sun sets in your area and adjusts the colour temperature of your screen to mimic the lighting in the room. Note that the Mac version’s interface isn’t as refined as its Windows counterpart — but it doesn’t matter very much because all of the time, the app is absolutely unobtrusive. There are no pop-ups and you won’t notice it running.

flux pref   Use F.lux To Sleep Better After Late Night Computer Activities

Here’s a short clip to show you how seamless the colour change is. I have to apologize for the video’s quality. The warming effect isn’t visualized in screencasts and I had to resort to using a digicam. The focus is invariably off. The point here is to show you that F.lux can actually warm the screen up quite a bit to compensate for the lighting conditions, especially if the room is lit with halogen or tungsten lamps. I can assure you that the colour changes evenly across the screen, even though it looks “top heavy” in the video.

I’ve been using F.lux for a while and I cannot instinctively tell when the warming appears. It’s a natural transition, which I appreciate. It can also be temporarily disabled in the menu bar to work on colour-sensitive projects. One more thing I have to stress: using F.lux doesn’t mean that you will fall straight to sleep once you’re off the computer and in the bed. No, there are other factors governing sleepiness. F.lux will only help reduce stimulated wakefulness and assist you in adjusting to lighting conditions.

If you find yourself skeptical, give it a try. F.lux is cross-platform and will work on Windows, Mac and Linux. If you think it works, share your experiences in the comments.

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Larry B.

This is great!!!

I used to adjust the brightness manually as I approached my sleep time… but this color adjustment is awesome.

Thank you once again, MUO

Jackson Chung

You’re very welcome


I’ve been using F.lux for ages now. Can’t imagine living without it.

One big, huge tip: Use it for at least a week before trying to asses it.

Jackson Chung

I totally agree and initially it takes a bit of getting used to


that what i needed , light hurts my eyes from injurious, i download this and it helped out a lot thanks


I just downloaded it, but it looks really interesting and hopefully it’ll help with that dreaded “wide eye” syndrome before bed :)


The “night” setting is to reduce eyestrain by lowering the overall brightness, not to reduce interference with your sleep-wake cycle.

Check out “Nocturne” for another app that is made for low-light computing.

Jackson Chung

You’re right, I didn’t phrase it properly. The Night setting is used to reduce brightness and generally compensate in the difference between the screen’s brightness and ambient lighting.


Great post, bro. Love this soft.

Anyway, the windows app is a bit diff from the previewed one right? o_O i dont see the windows you mentioned in the post… must be native to the mac app…


As in, i dont see the setting for the light bulb as shown above o_O


Anyway, one more comment: it doesnt work with full screen applications? o_O

Ginger Grapefruit

Thank you. I’ve been using F.lux for two days now, and I love it! The only suggestion I have for others is to set schedule of transition (under CHANGE SETTINGS) to “over 60 minutes.” Scheduling the transition to occur “over 20 seconds” was too abrupt–a shock to my nervous system, at 0700, when I had been up all night using computer.


hey thanks for the article! interesting! helpful!

do u guys know about similar free programs which allow to better customize.

F.lux dims my screen a bit too early…


…only thing i could do is define another place which is more east and has a 1-2h later sunset in relation to my real location.

Jackson Chung

Yeah, I was just going to suggest that to you. Glad you figured it out yourself!


anyways, that doesnt work too good. id need for the light intensity a sinus with a ‘streched peak’, which in the end doesnt mean a standard sinus that they use.

do u know about other programs?

i keep on clicking “disable for one hoer” haha :)


It’s good, I really like it, when I switch it off the difference is like “aagh my eyes”.

Is this good for the screen though?


I don’t think it can be BAD for the screen. It’s just a colour overlay.