There's a 10min break between every hour or two, and that's plenty of time to refresh your mind and/or get some snacks to eat. later on you might discover that one or two of those lectures are pretty useless and you can learn more efficiently on your own, so you don't go to them if you're tired.
I actually hate having lots of one hour breaks because there's not enough time to get much done and it's hard to schedule it so you have a few friends who also have breaks on that hour, so I normally try to schedule 2 - 3 hour breaks if in my schedule so I can get something to eat + catch up with a few friends.