Last night while falling asleep, my heart rate increased from resting to workout rate. a week ago, i took a caffeine pill for the first time. is there a connection between the two? when should i be worried? i only take regular supplements. thank you?

It is unlikely that the caffeine you took a week ago had any role in the increased rate last night. Unclear what you mean by "workout" rate. If your heart rate was in excess of 120 beats per minute, occurred abruptly and stopped abruptly, it is possible that the episode was paroxysmal tachycardia. You have to review your "supplements" and get advise regarding their safety.