Low Pulse Rate More Condition_symptoms Very Low Pulse Rate While Sleeping?

Very low pulse rate while sleeping? - low pulse rate more condition_symptoms

My resting heart rate on average during the day is about 70-80 beats per minute.
I know it is normal for your pulse to make a little time falling to sleep. But the other day when I woke up, my pulse was 44 beats per minute!
I read that the finely tuned athletes may have a weak pulse, but I'm definitely not a well-tuned athlete.
Is there another reason for a weak pulse in his sleep?
Thank you!