Do down comforters hamper sleep?

A possible cause of night terrors? For 3 nights in a row, my 4 year old started having night terrors, and the only thing I altered was the comforter. When I took the down comforter off on the 4th night and replaced it with a cotton sheet, the night terrors stopped. Coincidence? Probably not. He’s gone back to sleeping through the night and hasn’t experienced any night terrors since.
In my own personal experience, using a down comforter markedly hampered my deep sleep. The length of time I spent in deep sleep each night was halved according to the data provided by my Oura Ring (which is like a finger “Fitbit”) and my body temperature was higher than it had ever been while using the down comforter, but once I removed the comforter and replaced it with a lighter blanket, my body temperature and deep sleep went back to normal.

For more information on night terrors:
https://kidshealth.org/en/parents/terrors.html
Night terrors usually happen about 2 or 3 hours after a child falls asleep, when sleep moves from the deepest stage of non-REM sleep to lighter REM sleep. Usually this transition is a smooth one. But sometimes, a child becomes upset and frightened — and that fear reaction is a night terror. A night terror is not technically a dream, but more like a sudden reaction of fear that happens during the transition from one sleep stage to another.