You can watch Television before bed.
But it's recommended to stop watching Television at least an hour before bed to allow your mind to get into the resting state.
Watching Television too close to bedtime can mess with your bodies internal clock and potentially keep you awake and prevent you from falling asleep.
I used to watch Television while in bed but found I started losing sleep when doing so.
Now I watch Television before bed but turn the Television off 1 hour before actually falling asleep and I now sleep much better.