Hello and thank you for the question. We appreciate it and always recommend checking in with your doctor. Are you going through an anxious time or under a lot of stress or emotional pressure? This can be a reason for what you describe. Another common cause is obstructive sleep apnea which leads to lack of oxygen. Something else that can cause a rise in heart rate during the night is a dropping blood sugar. I know you are checking your oxygen but need to mention that. However, since it can also be associated with underlying coronary artery disease, it really is best to discuss this with your doctor to rule that out. By the way, are you taking any medications? And how are you tracking this?
Sorry for the typos. I could not figure out how to edit my post.