What's Happening While You're Awake?

At this point, we have a fairly high homeosthatic sleep drive because we've been awake nearly all day. As long as the circadian wake drive is still relatively high, we're still going to stay awake. And this persists until at some point later into the evening, at which point the cicadian drive for arousal fairly rapidly collapses. This corresponds to feeling pretty tiredand as i'm sure most people know, at some point in the evening you can feel fine. But then fairly quickly, you know, within half an hour or so, you're feeling very sleepy.