Thats natural human behavior. The biology term is 'arousal' and there are peaks in the morning and late afternoon, but around 1pm-ish your body naturally slows

Thats natural human behavior. The biology term is 'arousal' and there are peaks in the morning and late afternoon, but around 1pm-ish your body naturally slows down and wants sleep. The effect is much stronger in children, but it's there with adults. You don't feel like you could fall asleep because you've trained yourself not to, and you're most likely taking wakefulness promoting drugs all day.