When you sleep you less, your muscles feel rested. And your cardiovascular system also gets rest. Sleep deprivation does not give enough time for your body to rest and puts stress on your heart. It can also lead to high resting cortisol and adrenaline levels, similar to what you experience when you are stressed. So if you are an adult, get your 7 to 8 hours of sleep each night. Teens and young adults need more sleep and the recommendation is 9 to 10 hours.