Something that automatically adjusts the colour temperature of your computer screen can be helpful for a lot of people. They say the blue light emitted from screens tricks our brain into staying awake well past bed time.
I use Redshift and it changes the monitors output to be more biased towards red tones and in some ways mimics the natural red tones we see at sunset and helps us switch off and wind down for the day.
I use one of those too. I don't really find it makes as much of a difference as getting away from the electronics before bed but it's so easy to do that we should all do it! Great point @khufu!