If you are wondering whether your heart rate went up while you had that crazy dream last night, the simple answer is yes. In fact, whether you have a good dream or a bad dream, your heart and breathing rate always increase during a dream cycle. Your first dream cycle will typically occur 70 to 90 minutes after you fall asleep, and you will have several throughout the night.
A heart rate change while you are asleep is a clear indicator that you’ve entered a dream cycle. In fact, your heart rate, body temperature and breathing rate all speed up as you enter a dream cycle, according to “Dreams,” by Mary Herd Tull and Amy Ning. Your heart rate is likely to vary throughout this cycle and may speed up as much as 35 percent for short periods.
Dreaming seems to take lots of energy, note Tull and Ning, because your body goes into another deep rest after each dream you have during the night. As the night goes on, each dream cycle and its subsequent physiological changes, such as a higher heart rate, lasts longer. Your first dream is likely to last eight to nine minutes, whereas your last dream can be an hour long. You are likely to have a total dream time of about two hours if you sleep for eight. If your dream cycle sleep is disrupted, however, your body won’t follow the normal sleep cycle progression the next time you sleep. Instead, you may go directly into a dream cycle and have extended dream cycle periods until you "catch up" on this stage of sleep, according to the National Institute of Neurological Disorders and Stroke.
Your state of mind as well as your physical condition can affect your heart rate. This may be true even as you dream, says M. F. Madigan Jr., lead author of a study published in the journal “Perceptual and Motor Skills.” In his study, Madigan found that angry Type-A men have greater heart-rate increases during their dream cycles than non-angry Type-B men.
You can measure how much your heart rate changes during sleep with a heart rate monitor. Monitoring your heart rate may provide enough information to show what your breathing and sleep stages are throughout the night. In the past, sleep studies have used electrodes connected to a person’s head and torso to monitor muscle activity, brain waves and eye movement along with heart rate. New information from the American Institute of Physics, however, theorizes that heart rate monitoring is all that is really needed. The newer sleep analysis method uses a mathematical technique to analyze synchronization between heartbeat and breathing. This technique may even provide a measure of cardio-respiratory fitness, which may be useful for athletes who want to optimize their workout routines and as a tool for choosing treatments for people with cardiac diseases, notes PsychCentral.com.