Weight difference

why do I weigh less I weighed myself at 6am and then at 9am bc I went back to sleep lol and it was just for fun so pls someone don’t start w only weigh urself only at this time only this that I don’t care lol. I just happen to do this today and saw I was heavier at 6am and at 9am over 3lbs less. Both were both before drinking water using the restroom same clothes everything. and was just curious as to why 3 hours made a difference 😂