Brief Answer:
might be due to external environment.

Detailed Answer:
Hi
Welcome
I have gone through your query.
I would like to know since when you are facing this problem?
How is the climate at your place?
Do you mean to say that, your head sweat s lot at night?

I feel it is more related to the external environment rather than any illness.
Few suggestions
1. Maintain ambient temperature by using air conditioner.
2. Take a bath before going to bed at night preferably with cool water.
3.keep your bedroom cool by keeping your blinds closed all day.
4. You can try cooling bed pillows available in the market.

I feel with this measures, there should be some improvement.
This provisional advice provided by me is based entirely on the input provided to me. I would suggest examination by the doctor.

I hope this suggestion might be of some help to you.
Take care.

---