Do fluctuations in heartbeat denote heart disease?

Hi,

Welcome to icliniq.com.

No, fluctuations in a heartbeat do not denote any heart disease. In fact, it indicates that your heart is normal. Heartbeat should increase during awake, with activities and exercise. And, it should decrease with rest and sleep. However, you measures the pulse during rest and ask someone to do it during your sleep. The only concern is that it should not be too low. Here, the readings you mentioned are fine. Just to be on a safer side monitor your lowest pulse rate. I guess you do not have any symptoms like dizziness, fainting, palpitations, etc. In all probabilities, there is no abnormality in you and no need to worry.