With advancing years, I've experienced an increasing tendency to, when sitting down, drop off to sleep -- including when doing something which I enjoy and want to be awake for. This seems to apply above all, to the cinema; to the point that as of a few years ago, I've abandoned cinema-going -- it's simply ceased to be worth it. My last visit to the cinema was, a few years back, with relations, to see "Avatar": I found the film enthralling, but still nodded off a couple of times during it.
Re the discussion about the above -- whilst I've never, anyway, been an avid cinema-goer except for a spell late teens / early twenties: for a good many years I had a hang-up ("delayed adolescence", maybe) to the effect that it was shameful to "go places and do things" on one's own -- branded one as a sad "Billy-no-mates". This stopped me from seeing various desired films (and I've never "done" television, so films being shown on telly, has been little help); until I finally "grew up" re this matter, and came to the conclusion that it was a ridiculous thing to allow to govern one's doings.