Then other times you're not sleepy at bedtime. Know when you're sleepy and when you're not. Some people can organize days when you can listen to your own rhythms and be awake and asleep according to how you feel instead of what the hour is. Forget about having a formal meal for once. When you're sleepy the feeling may pass in a few minutes.
Confusion is a great source of sudden sleepiness.
If you feel sleepy, take a nap if you can. Wake up refreshed and ready to tackle the next tasks. Other times you may find yourself awake in the middle of the night, waiting for sleep or morning. Consider whether you feel like doing exercise at these times. Your body will tell you whether you have the energy or would rather rest and sleep.