<s>[INST] Hello doctor, I am a 20-year-old male. For the past several years my heart rate is as low as 48 while lying in bed. I have no symptoms. I am not an athlete. Should I be concerned? During the day it is around 70 bpm and with exercise, it gets to 160. It just gets to the 40s while I am in bed. Should I be worried about this? [/INST] Hi. Your heart rate is normal and this variation in heart rate during exercise and rest shows a healthy heart. Just keep your heart healthy for the rest of life by moderate exercise, avoid alcohol and tobacco, avoid stress and fatty meals. By following these measures you can enjoy a healthy life even in your 80s. This perfect healthy happy heart is a precious gift. Please protect your heart as heart will protect you too. </s>