Sleep; well it only happened once and I wasn't the only one. All my friends sitting in line with me fell asleep too and the general feel of the room made me wonder if others were sleeping!. The lecture wasn't boring or slow, it was just bad timing lol, there was a soporific effect that afternoon and it might not have been helped by a 6 (or 7) hour gap between lectures that day coupled with being warm. I had even had chocolate before to make sure I stayed awake but about halfway through I was really struggling to keep my eyes open and I slept for like the last 20 minutes.
I wouldn't recommend it though, so I'd say that i you're allowed to eat/drink in your lectures then have some fruit/fruit juice/water to keep you awake or those healthy energy bars to keep your concentration more focused.
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