Is Sleep Linked to Hypertension?
The link between sleep and hypertension is well-known. Studies have examined the effects of sleep deprivation on healthy volunteers and have examined the sleep patterns of people with hypertension, producing data that suggest adequate sleep may reduce risk. good cardiovascular health. Data from several studies show that people who sleep less than six hours each night are 20% more likely to develop high blood pressure.
One night of inadequate sleep in patients with hypertension has been shown to result in elevated blood pressure throughout the next day.
Average sleep times have declined
Our modern society runs 24 hours a day, and many of us curtail sleep time to keep up. From an average sleep duration of 8 to 9 hours in 1960, our national sleep duration has dropped to 6.9 to 7 hours. Many people try to get by on five to six hours of sleep nightly, a habit that may be contributing to serious long-term health conditions.
What happens when you sleep?
Sleep is restorative, most people agree. We usually don’t question why, but the fact is that the circadian rhythms of sleep regulate our nervous system and the hypothalamic-pituitary-adrenal axis, two critical body systems that keep our bodies in healthy balance. During sleep, normal people should experience a drop in blood pressure of about 15 points, on average. This reduces the work of your heart.
The Autonomic Nervous System and “Fight or Flight” Response
Sleep regulates the autonomic nervous system, that part of the nervous system that modulates the “fight or flight response.” This evolutionary response causes changes in many bodily functions that at one time were useful to provide an edge against predators.A constant state of preparedness from inappropriate activation of this response results in harmful stress on the body.
When the sympathetic nervous system is stimulated, blood vessels are constricted to deliver blood to vital organs like the brain and heart, increasing blood pressure. The “fight or flight” response is also associated with changes in glucose metabolism and an increased risk of insulin-resistant diabetes.
Cortisol, Adrenaline, and the Hypothalamic-Pituitary Axis
The primary hormones regulated by the pituitary and hypothalamus during sleep are adrenaline and cortisol, released by the adrenal gland. Adrenaline is a potent hormone that has a direct effect on blood pressure, mediated by constriction of the arteries. When your adrenaline levels remain high during the night, it can result in sustained hypertension.
Cortisol is a “stress hormone” that is highest in the morning and reaches a nadir between midnight and four AM. Lack of sleep can result in significant disruption of the cycle, subjecting your body to unnecessary stress responses and fatigue that are as damaging to your health as poor diet or lack of exercise.
When you awaken in the morning, your body typically experiences a 50% rise in cortisol level as your body prepares for the stress of a new day. Studies show that waking up early in the morning increases the cortisol response, an effect that is pronounced in people who are facing chronic stress and worry. Cortisol levels usually decline throughout the day, but in people who suffer from sleep loss, cortisol levels increase in the early evening, preventing natural recovery from the day and preparation for a restful night. In addition to lowered immunity, impaired glucose tolerance, and increased craving for carbohydrates, sleep deprivation is associated with elevated estrogen levels, decreased alertness, and poor concentration.
Sleep and Thyroid Hormone
Sleep loss also increases the amount of thyroid hormone in people who are not getting enough rest. People with elevated thyroid hormone have both increased blood pressure and cardiac output, putting unneeded stress on the heart.
Sleep, Obesity, and Hypertension
Sleep deprivation increases appetite by disturbing the regulation of leptin and ghrelin, two hormones that modulate appetite. Sleep deprivation alters your body’s ability to regulate the need for calories, resulting in over-eating and obesity, also linked to increased risk of hypertension.
Caffeine and Hypertension
Many of us use caffeine to remain alert when we haven’t slept well, a habit that causes dramatic increases in blood pressure. The mechanism for elevation of blood pressure after drinking a caffeinated beverage is not completely understood. Some researchers think caffeine may stimulate the adrenal gland to release adrenaline, a hormone with direct effects on blood pressure. It may block hormones that keep the arteries relaxed.
Obstructive Sleep Apnea
People who have obstructive sleep apnea (OSA) have multiple episodes during the night in which they stop and restart breathing. This disorder usually affects middle-age to older adults, but it can occur in patients of any age, particularly people who are overweight. People with OSA typically have high blood pressure, particularly on awakening, when their blood pressure should be at its lowest point. Symptoms of OSA include daytime sleepiness, loud snoring, morning headache, and difficulty concentrating during the day. They may be observed gasping suddenly during the night before returning to sleep.
Are You Getting Enough Sleep?
Sleep is critical for maintenance of your health. If you work shifts or curtail your sleep to accomplish multiple tasks, you are at risk for hypertension that can be difficult to treat. Measure your blood pressure in the morning. It should be at its lowest level and if it’s elevated, you should see your doctor in addition to consideration of lifestyle changes to prevent progression of medical problems associated with hypertension and sleeplessness. If you have symptoms of obstructive sleep apnea, there are effective treatments available.
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