Just noticed that iOS 9.3 beta 1 includes a setting for Blue Light Reduction under Display and Brightness. It basically starts to change the gamma of your screen down towards 2700K (adjustable with slider) at sunset and then pops it back to 5700K or so at sunrise. I'm not really prepared to go into the harmful effects of Blue Light on sleep and circadian rhythms but in a nutshell: The Primal Blueprint also discusses sleep and Blue Light Reduction so I was pretty excited to see this feature. How Light Affects Our Sleep | Mark's Daily Apple I started looking around for something similar for my wife's Mac and my Linux machines. Mac OS X = f.lux (settings are straightforward and I only adjusted the time of day she wakes and slid the colors around a bit) Linux = Redshift RS is available in most modern package repositories and pretty much works out of the box (I allow location so didn't have to set my lat and lon manually) I would imagine f.lux works on Windows too but I haven't checked. Example config file from the Arch Linux wiki Redshift - ArchWiki: Code: ~/.config/redshift.conf ; Global settings for redshift [redshift] ; Set the day and night screen temperatures temp-day=5700 temp-night=3500 ; Enable/Disable a smooth transition between day and night ; 0 will cause a direct change from day to night screen temperature. ; 1 will gradually increase or decrease the screen temperature transition=1 ; Set the screen brightness. Default is 1.0 ;brightness=0.9 ; It is also possible to use different settings for day and night since version 1.8. ;brightness-day=0.7 ;brightness-night=0.4 ; Set the screen gamma (for all colors, or each color channel individually) gamma=0.8 ;gamma=0.8:0.7:0.8 ; Set the location-provider: 'geoclue', 'gnome-clock', 'manual' ; type 'redshift -l list' to see possible values ; The location provider settings are in a different section. location-provider=manual ; Set the adjustment-method: 'randr', 'vidmode' ; type 'redshift -m list' to see all possible values ; 'randr' is the preferred method, 'vidmode' is an older API ; but works in some cases when 'randr' does not. ; The adjustment method settings are in a different section. adjustment-method=randr ; Configuration of the location-provider: ; type 'redshift -l PROVIDER:help' to see the settings ; e.g. 'redshift -l manual:help' [manual] lat=48.1 lon=11.6 ; Configuration of the adjustment-method ; type 'redshift -m METHOD:help' to see the settings ; ex: 'redshift -m randr:help' ; In this example, randr is configured to adjust screen 1. ; Note that the numbering starts from 0, so this is actually the second screen. [randr] screen=1 and my config: Code: [redshift] temp-day=5700 temp-night=2700 transition=1 brightness-day=0.9 brightness-night=0.5 gamma=0.8 adjustment-method=randr [vidmode] screen=N We now have all computer monitors and mobile device screens shifting from blue to red at sunset. We'll see if it makes a difference.