TeeVee make me SleePee

Watching TV make my brain go to sleep. It really does. I normally stay awake until at least 1 or 2am. Pretty much every night. Yet, last night and tonight after sitting watching the Commonwealth Games coverage, in which I’m taking an interest, I’m dropping off in my seat by 11pm. What it going on?
I can only imagine that it is because I’m being passive. When I normally stay awake until 1am or later, I am either reading, coding, browsing websites, emailing, or chatting. I’m using my brain, I’m actively engaged. Yet watching TV seems to turn off my brain. The funny thing is that I can watch a film through to the early hours. At least if it’s an interesting one, even if I’ve seen it before. So like books, films hold my interest.
It may also be true that sitting in the lounge means that I am not sat upright. The so -called comfortable seating in the lounge only allows one to slouch, leaning back. Whereas sitting reading in the kitchen or sitting at my computer I tend to sit upright with quite good posture.
So after falling asleep in front of the TV at probably around 10:30pm, I’m now sat in front of the computer feeling quite alert.
Very strange. Perhaps this explains why I don’t watch TV at all. I reckon that the nearly eight hours I’ve watched in the past two days has doubled my TV consumption this year!