[cassianoleal]

Whilst I don't think this is wrong in the general case, I don't think it's always right either. I commonly watch movies or series on my phone or tablet in bed. Always with a very dim screen and very low volume - and also with night shift on, or whatever it's called.

Sometimes I wake up in the middle of the night to go to the bathroom and can't sleep straight away, so I watch a bit more TV on my phone, maybe up to 1h or so, and then go to sleep again.

Some of my best nights have been that way. 7-8h in total sleep, with screens before and during this time. Some of those nights were so good that I didn't even feel like having a coffee during the day, and didn't feel any sleepiness or fogginess at work.

To me, the 2 things that have the greatest impact on my sleep quality are what and when I've eaten the day before; and how and how much I moved. A long walk is usually enough, whereas strenuous exercise (a long and hard climbing session for instance) can be disruptive to my sleep due to the muscle inflammation.