The Effect Of Caffeine On Rem Sleep Heart Rate

Science has not yet solved all the mysteries of sleep. While many plausible theories seem to explain why your body and brain need it, there are questions that have not been answered with scientific proof. Why do some people need more than others? What happens biologically while you're doing it? The importance of sleep itself, however, isn't debatable. Nor is the importance of Rapid Eye Movement, or REM sleep, the stage of sleep that induces dreams. Your body and brain undergo vital chemical processes at every phase of sleep, including REM. Caffeine, and its effect on your heart rate, may negatively impact the quality of your REM -- and therefore your health -- in ways known and unknown.

Your Heart and Your Sleep

Your body begins winding down, preparing for sleep, well before you're actually in dreamland. Once you're asleep, your heart rate -- though lower overall than when you're awake -- varies with each of the five phases of sleep you move through. While your overall heart rate is lower, the degree to which your heart rate varies from one phase to another is greater than the degree of heart rate variability normal when you're awake and at rest. In a 2005 peer-reviewed paper for Portland State University, biology scientist Payel Ghosh concluded that "further investigation of heart rate variability of subjects in different postures" were needed to better understand the physiology of sleep.

Your Heart on Caffeine

Whether you get it from coffee, chocolate, energy drinks or another source, caffeine gives you a boost. You may associate that boost with your brain -- a heightened feeling of alertness -- but the Healthy Sleep website warns that it also raises your heart rate. The faster your heart is beating when you sleep, the more difficult it will be to reach the deepest levels of REM and, if you get there, your increased heart rate may pull you out of it before you've had enough.

The Adenosine Battle

When your eyes get heavy and your body yearns for bed, a chemical in the brain called adenosine is to blame, according to"The Harvard Medical School Guide to a Good Night's Sleep." The longer you're awake, the more this molecule builds, and caffeine is a common weapon for fighting its effects. Authors Lawrence Epstein and Steve Mardon explain that caffeine remains in your bloodstream three to five hours after you consume it. This, in addition to increased heart rate, may harm the quality and quantity of REM sleep.

Sleep on This

Further complicating the issue of caffeine's effects on heart rate and REM is the fact that caffeine is an addictive drug, and many people may be allergic to it. Medical Laboratory Technician Ruth Whalen writes for DoctorYourself.com that symptoms of a caffeine allergy may be mild, but may also be so extreme that they resemble Attention-Deficit Disorder, bipolar disorder, psychosis or schizophrenia. If your heart and your sleep don't feel right and you habitually use caffeine, consult a health-care physician to talk about moderating or stopping your use of caffeine.