Computers and phones can be used to aid adaptation, but there are also certain precautions that should be taken when using them, especially during the dark period. This article details how to use software such as screen filters on your computer during the dark period and gives examples of some programs that have been used by the people in the polyphasic sleep community with good results. Alarm applications, Napchart, usage trackers and todo-list applications are also discussed.

Screen filters

Screen filters, which are programs that alter the colour of computer and phone screens, can be used during the dark period. Red glasses are usually preferable as they block blue light from all sources, however screen filters are a suitable substitute if the glasses are not an option for you. As non-red light frequencies have the largest effect on circadian rhythm alignment, they should be blocked off during the dark period. Ideal setting for screen filter programs is below 1000K, and preferably below 2000K (which is the temperature of candle light). The color distortion created by the screen filter software should not be compensated for by increased brightness as that will proportionally increase the effect on the circadian alignment.

f.lux (Windows, Mac, Linux, Apple)

Based on GPS coordinates, f.lux automatically adapts the computer screen colors to be identical to the ambient light at the exact geoposition of the user. Thus, ideally, the colors of the computer screen are adjusted to be the exact colors necessary to impress the optimal stimulus on the brain’s circadian rhythm.

The appeal of f.lux lies in its easy configurability and automatic process: Change the GPS coordinates to your current location and the rest is taken care of by the program. It is also possible to manually adjust the colors close to the desired temperature of your choosing. The temperature range is from 1200 K to 6500 K with eight possible choices: 1200 K, 1900 K, 2300 K, 2700 K, 3400 K, 4200 K, 5500 K, 6500 K. Pressing Ctrl+Alt+Page Up/Down will increase/decrease the temperature by 250K all the way down to 800K, and after reaching 6500K the temperature is increased in 500K increments up to a max possible temperature of 100000K

The interface looks as follows:

The Sun’s daily cycle is represented by the blue/red line, indicating when the sun is up (blue) and when it is down (red), and the short transitory period in between. The color temperature is displayed above the timeline.

Opening the menu produces the following:

Each menu item is self-explanatory and extremely easy to use even at first use.

I have used f.lux for since its initial release in 2009, and I have been extremely happy with its color manipulation ability on all of my computers. In fact, I have made sure to install that as my first application after having purchased a new computer. I will not use any other color manipulation application.
(Discord user Bobby)

Redshift (Mainly Linux)

Redshift is the easiest screen filter program to set up on Linux that provides colour temperatures down to 1000K. It only supports Xorg. For Wayland, you might want to use the Night Light feature in GNOME. Download this from your favourite package manager. Even though redshift does have a GTK frontend available, it does not provide

> Start by copying this file to your $XDG_CONFIG_HOME/redshift/redshift.conf

> With your favourite editor open the file and change the following:

  • temp-night=1000
  • dusk-time={when you want the screen to start transitioning}-{start of your dark period}
    • g. dusk-time=19:40-20:00
    • and set dawn-time in the same way
  • Comment out the two lines under [manual]
  • You might also want to disable it during the day. To achieve this, set temp-day=6500

See man redshift(1) for more information.

Sunsetscreen (Windows)

Sunsetscreen is free, easy to use, and intuitive. Everything you need is located on one panel, and you’ll likely never need to touch it again unless your sleep schedule changes.

In the Night Colour tab, bring down the filter to 1000K and adjust brightness to preference. Set the sunrise time to when your dark period ends, and adjust the delay until sunset to start when your dark period begins. An optional (but recommended) transition phase slider can be chosen as well. The defaults for daytime should need no altering.

This program is incredibly simple to use and has all the customisation you will need in one panel.

 Twilight (Android)

Twilight is a free and easily customisable application for your phone. It has a pleasant and easy to use interface and all the features you need for your dark period.


This is the menu you will get upon opening up Twilight through the expanded notifications bar. Expanding the profile button will get you a list of all your saved presets. Pressing either settings or the app icon will bring you to the full menu. Pause will stop the filter from running, and is useful when you need to download apps. You will not be able to approve permissions for downloads unless Twilight is paused or disabled.


This is an example of a profile for a Segmented to DC1 gradual adaptation. Twilight can function both by automatically checking your location with GPS, or with a purely customized dark period. This one is set up to be 12 hours, and has an hour of transition on both ends included to mimic sunrise and sunset. Color temperature affects red light, Intensity affects how strong the red light filter is, and screen dim affects overall brightness. Bring down the red light to 1000k; the rest can be done to preference.

For $2.99 USD, you can purchase the unlock for Twilight. This allows you to add more than two settings presets, change the transition time to something other than an hour, and the option to disable Twilight when not during your dark period (normally it is always running). This isn’t necessary and Twilight free does not have ads, but consider supporting the developers.

Vision (Windows)

The complete filtering of green/blue light has an effect similar to green-blue color blindness, or tritanopia. Vision is meant to help alleviate the problems of green/blue color blindness by mixing some red into green colors, making red colors somewhat brighter red, and generally allows you to see some contrast between blue and green things on your screen. This works well in combination with the red laser goggles if you can not block all blue/green light in your room.

Negativescreen (Windows)

This program gives a low-level control over filters with convenient hotkeys.

It is ready to use right after downloading, just use the filters listed below. Clicking it toggles the filter on and off, and right-clicking allows for selecting a specific filter, for exiting, and for editing the configuration file. Included here are two custom filters; Red, and Inverted red. Here is what they each look like:



Inverted red

In order to use them, take a look at your configuration file, and modify it so that it looks like this:


# Matrices

{    0.8, 0, 0, 0, 0 }
{    0.3, 0, 0, 0, 0 }
{    0.2, 0, 0, 0, 0 }
{      0, 0, 0, 1, 0 }
{ -0.126, 0, 0, 0, 1 }

Inverted red=win+alt+F2
{ -0.4326, 0, 0, 0, 0 }
{ -0.4336, 0, 0, 0, 0 }
{ -0.4338, 0, 0, 0, 0 }
{       0, 0, 0, 1, 0 }
{  1.1740, 0, 0, 0, 1 }

You can have NegativeScreen run on startup, just change the ActiveOnStartup to true. You can also have it run when you press a key combination, like Windows key + Alt + Space as exemplified above. The ColorMatrix viewer (also linked to, within the NegativeScreen page) is helpful for creating your own personal filters, though people should not need additional ones than those listed above during the dark period. Here is a useful resource for better understanding color matrices.


(See “Products” for information about the recommended alarm setup).

This section discusses different options of alarm applications that can be used alongside or instead of mechanical alarms. It is important to have multiple devices scattered around and not just a single alarm even with a well set up software alarm. If you wear headphones while sleeping (perhaps to avoid waking up a sleeping partner next to you) the best option is using an app that outputs the alarm sound only into the headphones, and another app that outputs the sound in both the headphones and phone (or just the phone). This is because people tend to unconsciously remove the headphones in their sleep, usually due to discomfort, and being able to hear an alarm is essential to wake up in time. The backup alarm can be set a few minutes after the main one.

Making use of barcode alarms is also recommended. The barcodes can be placed in various tactical places, like in the shower (to signal for you to take a shower), in the fridge (to signal drinking a glass of cold water) and so on.

Here is a list of phone alarm applications:

  • Alarmy (headphones/device)
  • Sleep as android (headphones/device)

StayAwake (Linux, Windows)

StayAwake is a simple inactivity alarm program based on PyQt. It tracks your activity by detecting your mouse clicks and keyboard presses. If a custom defined period is reached without a user event  it will sound an alarm. It also supports other features such as automatically turning off the alarm system during your predefined sleep period and suspending operation temporarily.

Although this piece of software has existed for some time already, help is needed for testing. If you encounter any problems or have any suggestions, please open a github issue or contact zandimna#3117 on discord.

WARNING: Excessive use of alarms, especially with earphones at high volumes can lead to hearing damage and tolerance to alarms. The alarm is meant to be a tool to prevent accidental oversleeps, not to maintain wakefulness through an entire period of sleepiness. You are advised to switch to a more stimulating activity if the alarm sounds more than five times in a given hour.


This site can be used to create a visual chart of your sleep schedule. This can be particularly helpful if you need a reminder of scheduled sleep and set the napchart as your background.  Napchart is also a preferred way in the community to easily share schedules.



Usage trackers

Usage trackers are applications that track how long you’ve been on your computer/phone are great for knowing if you overslept or stayed awake (and if you do oversleep they can help you with preventing it in the future, as they can give an idea of what you did wrong). It is recommended to get one app for your phone and for your computer, if you’re using both of these during the difficult times of your adaptation.

Additionally, usage trackers can often be used to see what types of activities you performed at certain times, which allows you to see whether you performed activities that required focus or could be done half asleep. For example, this can be a way to check that you haven’t been microsleeping repeatedly during periods which are known to be difficult.

Manictime (Windows)

A usage tracker for Windows computers. It is Ideal if you spend all day with a single computer, and useful if you have a good idea when you usually spend time on your computer. A popular way to use it is to compare the active and inactive periods with your sleep schedule, and seeing if inactivity lines up with sleep or specific activities you remember doing away from your computer.

The software doesn’t detect short bouts of inactivity very well, so it is likely not a good way to track microsleeps ranging from seconds to several minutes in length, but you can try to find times where you’re likely to microsleep with it based on activities you performed.

To-do list

Having a good reason to sleep polyphasically, for example work taking a lot of time, is going to be very helpful in order to adapt successfully. One’s mental powers usually only go so far if there is no important reason why more time is needed. To help with this, setting up a software application that works as a to-do list or physically writing a to-do list can help you have activities planned out to help staying awake and reminding you of the reason you want to sleep polyphasically in the first place. [Adaptation] has a list with good activities that can be done to avoid oversleeping during adaptation. To-do-list applications should not be hard to find by simply searching the internet.

Main author: Crimson

Page last updated: 8 January 2020