u/Competitive-Can-2069

I (21F) have so much trouble sleeping with my bf (20M). We fall asleep together completely fine, neither of us snores, and as far as I know we don’t wake each other up. But the day after I stay over I am absolutely exhausted, even after sleeping for 8-9 hours and going to bed early. I love sleeping with him so much and really don’t want to use seperate beds but the follow day I am barely able to function and do my uni work, sometimes even falling asleep. When I sleep alone I feel perfectly well rested. What could this issue possibly be from?