It's very cold. I can't sleep after taking a nap.

There are many reasons for not taking a deep nap: the most common reason is that people are too excited to fall asleep. This may be because the weather is hot, people's metabolism is faster, or it may be because the subconscious mind forces them to fall asleep.

I suggest that you try to do something relaxing before going to bed all afternoon, and try not to cause nervous excitement, such as listening to some light music or reading some boring books.

If you can't sleep at night, you can try to keep your brain blank or do strenuous exercise before going to bed (although experts object to doing exercise before going to bed, I will fall asleep because of exhaustion, which of course varies from person to person)