The blue light in all your devices (phones, tv, computer) all generate blue light which messes with your circadian rhythm by stimulating your daytime hormones like cortisol and disrupting the increase of melatonin which should start to happen naturally a few hours after sunset. We suggest clients stop using their devices an hour before bed and if they do watch TV to wind down and still struggle with sleep it is a good idea to purchase blue light blocking glasses, particularly if you have fluorescent and LED lights at home.
If you need to use your computer there is a great app you can download called F.lux which removes the blue light as well as turning your phone on night mode. Besides the concerns with blue light it is also important to look at what you are doing on screen- most of the time screen activity is firing up your brain- sending emails, playing games, looking at social media which is not ideal before sleep.