Whether it wakes you up from a deep sleep or prevents you from falling asleep in the first place, a pounding heartbeat can be distracting and frightening. In some cases, a pounding heart rate at night is relatively harmless and only happens occasionally. In other cases, however, a pounding heart rate at night could indicate a serious condition.
Low Blood Pressure
Although the heart controls blood pressure, blood pressure in turns controls the heart. Blood pressure refers to the force of blood against the walls of the arteries. For most healthy adults, blood pressure tends to be lowest at night when the body is at rest. Your blood pressure slowly begins to rise upon getting out of bed and tends to peak during the afternoon. Although blood pressure regularly lowers at night, few people experience problems. In rare cases, however, the blood pressure drops so low that the body cannot receive adequate amounts of blood. In an attempt to meet the body's needs, the heart beats faster to deliver more blood. In severe cases of low blood pressure, the heart may beat so quickly that it seems to pound inside your chest.
Low Blood Sugar
Along with shakiness, dizziness and confusion, a rapid heart rate is one of the most common symptoms of low blood sugar. Also referred to as hypoglycemia, low blood sugar is a dangerous condition, particularly among patients with diabetes. The body depends heavily on sugar, which it uses to provide energy and perform necessary bodily functions. When sugar levels become too low, the body cannot function properly and the heart races in an attempt to fix the problem. Low blood sugar may result from skipping meals, exercising excessively or receiving too much insulin.
Heart palpitations and a racing heart rate are common side effects of a wide range of drugs and medications. For example, the medications used to treat asthma and high blood pressure often cause the heart to beat quite rapidly. Although nicotine and caffeine are typically not thought of as drugs, they also fit into this category. Upon entering the body, nicotine and caffeine stimulate the central nervous system. During the day, you may not notice the excess stimulation since your body is in motion and your mind is focused elsewhere. However, this stimulation becomes extremely obvious at night when your body is at rest. If you frequently take medications, smoke cigarettes or drink caffeine in the evening, try to do so at least three to four hours before bedtime.
Nightmares and Night Terrors
Most people have experienced nightmares at some point in their lives, causing them to wake up abruptly with a racing heartbeat, quick respiration and sweat on the forehead. Although night terrors also involve frightening and vivid dreams, people experiencing night terrors remain asleep throughout the entire episode and rarely remember the dream upon waking. Oftentimes, nightmares and night terrors are relatively harmless. Although they may temporarily cause increased heart rate and respiration, the pounding heart rate quickly returns to normal upon waking. However, consult a physician if the nightmares or night tremors frequently disrupt your sleep or lead to injury.