Physical Health

A good night’s sleep is vital to your physical health. During sleep, your body and brain recover (1) from the previous day and prepare you to wake up refreshed in the morning. Lack of sleep reduces this much-needed recovery time, and chronic sleep loss can increase your risk for certain diseases and adverse medical conditions. Surveys suggest more than one-third of U.S. adults (2) get less than the recommended seven to eight hours of sleep (3) each night.

Not getting enough quality sleep can affect your physical health in a myriad of ways. In this guide, we’ll cover some of the most common physical health issues that stem from inadequate or low-quality sleep.

Sleep and Obesity

The circadian rhythms that guide your 24-hour sleep-wake cycle also help facilitate other bodily functions (4), including production of hormones for appetite and digestion. Sleep also plays a role in regulating your metabolism (5). Not sleeping enough can lead to increased production of ghrelin (6), a hormone that elevates your appetite, and decreased production of leptin, a hormone that suppresses your appetite. This can cause you to feel hungrier than you normally would after a good night’s sleep.

Some brain imaging studies also suggest poor sleep can essentially change the way you perceive food (7). Specifically, not giving your brain enough time to recover during the night may increase your central neuronal responses to unhealthy meals and cause you to overeat. This is known as hedonic eating, as opposed to healthy hunger-driven eating. Another issue for people with limited sleep durations is that they are awake more during the day and have more opportunity to consume food.

Inadequate sleep can also decrease your tolerance for glucose and cause insulin resistance. This elevates your risk for Type 2 diabetes, a disease characterized by high glucose levels (8) in the bloodstream. Insulin transports glucose from the blood into different cells located throughout your body. When your body is resistant to insulin, the glucose remains in your blood. Type 2 diabetes is a chronic, lifelong health condition. Patients can manage the disease with a healthy diet and regular exercise, but there is no cure.

People with Type 2 diabetes are at higher risk of developing a sleep disorder. A large percentage of Type 2 diabetes patients have also been diagnosed with sleep apnea (9), a condition that causes sleep-disordered breathing. Roughly 20% of these patients (10) also have restless legs syndrome (RLS), which is characterized by painful sensations in the legs while the body is at rest. People with RLS feel as if they must constantly move their legs during the night to alleviate this sensation.

Sleep and Heart Health

Poor sleep can negatively affect your heart health. Blood pressure naturally decreases (11) as part of the bodily shutdown that occurs during your sleep cycle (12). If you don’t get enough sleep, then your blood pressure spends more time at an elevated state during the night. Over time, this can lead to the condition known as high blood pressure (13), or hypertension. Long-term high blood pressure increases your risk of heart attack, stroke, heart failure, and kidney failure.

Lack of sleep has also been linked to increased inflammation (14), an immune system response to sick or damaged tissue. Swelling, or blood cells healing the tissue with fluid, is the immune system’s way of repairing the tissue and isolating the affected area from the rest of the body. Proper sleep promotes healthy production of cytokines (15) that help facilitate the inflammatory response. Conversely, inadequate sleep may reduce your cytokine levels and affect how your body responds to bacteria, toxins, and other foreign substances that are harmful to your body.

Although the inflammatory response helps you stay healthy, too much inflammation over time can damage the heart (16). Different types of heart inflammation (17) include:

  • Endocarditis is an inflammation that affects the inner lining of the heart’s chambers and valves, which can prevent steady blood circulation.
  • Myocarditis is an inflammation of the heart muscle that hinders your ability to properly pump blood and can lead to heart failure.
  • Pericarditis is an inflammation of the pericardium, or tissue sac that encloses the heart, which can expose the heart to infection.

Blood pressure, heart rate, and other cardiovascular functions align with circadian rhythms (18). People who follow irregular sleep patterns that are not synchronized with 24-hour circadian cycles – such as those who normally work night shifts – are considered at higher risk of heart disease and stroke.

Sleep and the Immune System

The relationship between sleep and immunohealth (19) is bidirectional. Adequate sleep recharges your immune system, and a healthy immune system helps you sleep better. People who get enough sleep generally have a lower risk of infection, better outcomes when they do get sick, and a stronger response to vaccinations. Sleep also promotes a healthy inflammatory response through production of cytokines.

Poor sleep can impact both sides of this bidirectional relationship. For example, sleep disruptions can weaken the immune system and exacerbate symptoms of conditions affecting the gastrointestinal system, such as inflammatory bowel disease, irritable bowel syndrome, and gastroesophageal reflux disease. In turn, heightened symptoms of these conditions can make it harder to fall or stay asleep during the night.

Sleep is also believed to play a role in strengthening immunological memory (20), or the immune system’s ability to remember certain infections and the most effective ways of responding to them. Specifically, your immune system most likely forms memories during the third stage – or slow-wave sleep (SWS) stage – of your sleep cycle, during which deep sleep occurs. Sleep disruptions (21) are more likely to occur during the first two stages, so interrupted sleep may limit your time in the slow-wave stage and weaken your immune system’s ability to process memories.

Immunological memories are particularly important to the way your body responds to allergens. Recent studies suggest a link between circadian rhythms and severity of allergy symptoms. If you have an allergy and your circadian cycle is interrupted, you may be at higher risk of a serious allergic reaction. In one study, sleep deprivation was found to increase susceptibility of a peanut allergy attack (22) by as much as 45%.

Sleep and Addiction

Long-term sleep deprivation can decrease regulation of dopamine receptors (23). Dopamine is a hormone that plays a role in many different daily processes related to movement, emotions, and the brain’s reward system (24). Two critical functions of dopamine receptors are decision making and impulse control. When regulation of these receptors is reduced, you may be more likely to make poor decisions regarding drugs, alcohol, and other addictive substances.

Conversely, addictive substances can interfere with a healthy sleep cycle. Certain narcotics such as cocaine and methamphetamine are addictive because they interact with dopamine pathways in the reward system. Over time, repeated stimulation can cause major sleep deprivation. Other less addictive stimulants like caffeine and nicotine (25) also interact with the dopaminergic system and can lead to poor or inadequate sleep.

Addictive substances, known as depressants, also negatively impact sleep, albeit in different ways. Alcohol, for instance, creates feelings of sleepiness (26) that can make you feel tired or groggy. This has led many to believe alcoholic beverages are conducive for sleep. However, consuming alcohol before bed can prematurely induce deep sleep and interfere with your sleep cycle. Studies have also linked alcoholic beverages and a higher incidence rate of sleep apnea.

The vicious cycle of substance abuse and sleep problems can take an unhealthy toll. One survey found that more than one-third (27) of people with substance abuse disorder slept fewer than seven hours each night. Nearly half of respondents claimed to regularly snore, and about 38% admitted to unintentionally falling asleep during the day.

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If you are not getting enough sleep and experiencing any sort of health problem as a result, we recommend making an appointment with your doctor. They can help pinpoint problematic sleep habits, diagnose health problems stemming from poor sleep, and evaluate you for a sleep disorder.

References

+ 27 sources

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