Sleep is an important part of the day but approximately one third of Americans do not get adequate sleep. This could ultimately lead to hypertension, heart artery disease, atrial fibrillation, and early death. So, what can be done to get a good night’s sleep?
The normal sleep cycle consists of four stages. There are three stages of non-REM (rapid eye movement) sleep, each lasting 5-15 minutes. Stage 3 of non-REM is the deep sleep stage where the muscles, tissues of the body and the brain are refreshed from the stresses of the day, bone and muscle are built and the immune system is strengthened. During the REM stage, the eyes move rapidly from side to side, the muscles are often paralyzed, and the brain is more active than in stage 3. Dreaming occurs during REM sleep and a person can dream 4 to 6 times per night.
There are a variety of sleep disorders; the most common are insomnia and sleep apnea. Insomnia is difficulty falling asleep and staying asleep. It may be due to psychological stress, excessive mental activity at bedtime, inconsistent bedtimes or caffeine or heavy alcohol intake in the evening. It may be treated through behavioral modifications, exercise, and avoiding stimulants in the evening. Medications can be helpful, including sleeping pills and melatonin. Melatonin is a hormone produced by the pineal gland in the brain and it helps regulate the sleep-wake cycle. It is also available as an over the counter medication used to shorten the time to sleep. Nowadays, one of the biggest causes of insomnia is the use of electronic devices near bedtime. It has been found that the light exposure from these devices affects the normal sleep cycle. The light emitted suppresses the secretion of melatonin. This causes a later sleep time, increased alertness at bedtime, reduced REM sleep, and increased morning sleepiness.
Sleep apnea is a condition characterized by periods of decreased breathing while sleeping. Obstructive sleep apnea occurs when air movement into the lungs ceases causing the oxygen level in the body to fall. This prompts the person to wake up and take deep breaths. These periods of apnea disrupt the sleep cycle and prevent the person from getting enough time in the restorative stages of sleep. Because the body does not get enough rest, the person feels “revved up” all the time. It is associated with loud snoring, excessive daytime sleepiness, morning headaches and irritability. Sleep apnea is also associated with significant heart problems including hypertension, stroke, heart failure, blockage in the heart arteries and atrial fibrillation. It is diagnosed by a sleep study, which counts and measures the periods of apnea and low oxygen. Treatment of sleep apnea primarily involves weight loss and CPAP. Treatment with CPAP is especially useful in lowering blood pressure and preventing recurrent episodes of atrial fibrillation and congestive heart failure.
Just as important as sleep is the process of waking up. When one is woken suddenly and too early, there is a prolonged period between the eyes opening and being fully awake. This phenomenon is called sleep inertia, a groggy sensation somewhat like jet lag. This is because the brain’s arousal system is activated almost immediately but the higher centers of the brain take longer to awaken. Sleep inertia can take anywhere from 2-4 hours to resolve. Waking up naturally, is much better for us. The mismatch between our biologically optimal wake up time and the alarm clock time takes a toll on our system, leading to obesity, diabetes and heart disease.
So, what is the optimal amount of sleep needed for a long and healthy life? In one study, examining patients 40-54 years old and who were free of heart disease, those sleeping less than 6 hours or more than 8 hours per night had higher risk of plaque in the heart arteries than those sleeping 7 to 8 hours. In another study of patients over 60 years old, those who slept less than 6 hours had a 12% increased risk for death and those who slept more than 9 hours had a 30% increased risk of death. In this population as well, 7 to 8 hours was the optimal amount of sleep time. However, very different results could be found if younger populations are studied.
Bridgewater resident Steve Georgeson is a cardiologist who works for Medicor Cardiology. Here, he writes about topics and events pertaining to cardiology.