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It is estimated that about 10% of the population have undiagnosed sleep apnea, which may be an underlying cause of heart disease. People with sleep apnea suffer from repeated obstructions of the throat during sleep. They literally can't breathe while sleeping. They must wake up in order to breathe (but they don't usually recall these awakenings). This repeated fragmentation of sleep patterns keeps them from having normal, restorative sleep. Recent research suggests that snoring itself may affect sleep quality and may respond to the same treatments used for apnea.
One way sleep apnea is linked to heart disease is through its effect on blood pressure. Research has shown that apnea patients with normal blood pressure run a risk of developing high blood pressure within four years. Hypertension is a major risk factor in the development of heart disease and stroke.
Apnea patients have higher levels of sympathetic nervous system (SNS) activity during both wake and sleep than patients without sleep apnea. Involuntary functions such as heart rate and blood vessel constriction are controlled by the sympathetic nervous system. In persons without apnea, there is usually a decrease in SNS activity and blood pressure falls when sleeping. However, during apnea events, the higher level of SNS activity constricts the blood vessels, while the heart rate also jumps, slamming blood into tight vessels. Blood pressure spikes of up to 250/150 have been seen during apneas.
Sleep apnea patients also have faster heart rates than non-apnea patients, even when awake, but have less variability in their heart rates. This combination of a less variable heart rate and greater variability in blood pressure is an indicator of potential cardiovascular problems.
Lastly, a condition known as central apnea may cause high blood pressure, surges of adrenaline, and irregular heart beats. Central apnea occurs without snoring and is not caused by obstruction, rather it is caused by the failure of the brain to signal for a breath.
Preventing Heart Disease by Treating Sleep Apnea
One method of preventing heart disease therefore is to treat the underlying sleep apnea, of which a major symptom is snoring and daytime fatigue. Successful treatment of sleep apnea {usually with nasal continuous positive airway pressure (CPAP)} may play a significant role in preventing hypertension and heart disease. Since a major symptom of sleep apnea is snoring during the night and excessive daytime sleepiness, it is important to establish that you have the correct diagnosis. It is therefore important to talk to your primary care clinician about your sleep problems and take a proactive role.
After losing at least 10% of your body weight, consider undertaking another sleep study to determine further treatment.
Note: This is part three of a five-part series of short articles on sleep and health. In the next newsletter Dr. Siddique's article will be titled "Cardiovascular Consequences of Sleep Deprivation".
About the Author: Dr. Siddique is a Clinical Associate Professor of Medicine at UMDNJ- Robert Wood Johnson Medical School and Medical Director of the SleepCare Center at RWJ Hamilton. He is also the President of the Institute for Sleep and Lung Diseases. He is board certified in Internal, Pulmonary, Critical Care and Sleep Medicine. He has received multiple “Excellence in Teaching” awards at RWJ Medical School. He was selected to be on the peer-nominated Best Doctors list in Better Living magazine in NJ. He is also co-author of the book, “How to Turn Anger into Love” (www.HowToTurnAngerIntoLove.com). He can be reached at: (609)587-9944; www.sleephealthdoc.com.
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