A good night’s sleep is one of the simple joys of life. However, sleep is like everything else: few people truly appreciate it until they lose it. Unfortunately, too little sleep or poor-quality sleep can have some serious health ramifications. In fact, researchers are consistently finding new evidence to support the importance of sleep.

Why do we need sleep?

Two leading theories seem to explain why the body needs sleep.

First, it’s believed that sleep is restorative, allowing the body to repair and rejuvenate itself. Restorative functions, such as muscle growth, tissue repair, growth hormone release, and protein synthesis, all take place mostly (or sometimes only) during sleep. Additionally, in studies with animals deprived entirely of sleep, the animals lost all immune function and died in weeks. These findings all suggest that sleep is vital to the body’s self-maintenance.

The second theory concerns brain plasticity, or changes in brain structure and organization. The brain carries out three functions when learning or memorizing something new: acquisition, consolidation, and recall.

Acquisition is the introduction of new information, like the delivery of a stack of file folders. Consolidation is the process during which the information or memory is made stable, which can be thought of as those file folders being arranged in file cabinets. Recall is the brain’s ability to access the information or memory after it’s been stored, like reaching into a file cabinet and retrieving a specific folder. All three functions must take place for learning and memory to take place. Acquisition and recall only happen during wakefulness, but researchers believe that consolidation can only occur during sleep.

There are other theories supporting the importance of sleep, but these two have a substantial amount of supporting evidence. Some scientists are beginning to suspect that both theories are accurate, suggesting that sleep is vital to every part of the body from head to toe.

Sleep deprivation

Sleep deprivation is associated with some serious health risks.

Sleep is vital from day one. Researchers have found that even infants and children have an increased risk of obesity and overall body fat if they get less than the recommended amount of sleep before age seven. It’s unclear so far exactly why sleep deprived infants and children are more likely to be obese or have more body fat. It’s possible the lack of sleep causes obesity (potentially by affecting hormone levels), but it’s also possible that the lack of sleep affects decision making, which leads to children choosing unhealthy eating habits.

The same pattern is apparent in adults, too. Obesity or being overweight is one of the biggest risks of sleep deprivation. It’s thought that lack of sleep can trigger the release of a peptide that stimulates the appetite – specifically, sleep loss seems to stimulate cravings for high-fat, high-carb foods.

Additionally, sleep deprivation increases the risk for numerous health issues, such as:

  • Heart disease, attack, and failure
  • Irregular heartbeat
  • Stroke
  • Diabetes
  • High blood pressure

Some estimates suggest that 90% of people with insomnia also have another health condition. People suffering from lack of sleep are also at a much higher risk for car or workplace accidents. In fact, the loss of the space shuttle Challenger was attributed largely to poor judgement resulting from extended shift work and tiredness.

Sleep deprivation also leads to impaired memory and decision-making, causes the skin to age faster, and reduces sex drive. The risk for mental disorders, such as anxiety or depression, is also higher for those who are sleep deprived. One study actually found that lack of sleep is linked to the negative repetitive thoughts that characterize many mental illnesses, suggesting that a lack of sleep might contribute to the development or worsening of mental illnesses.

Chronic pain and sleep

Getting enough healthy sleep is especially important for people who suffer from a chronic pain condition.

Sleep deprivation lowers the pain threshold. This means that the more tired an individual is, the more likely he or she is to experience sensations as painful. The increased pain can make falling asleep and staying asleep difficult, which often leads to more sleep deprivation. This becomes a repeating cycle, until it’s difficult to tell which came first – the sleep deprivation or the pain. Often, this is when mental disorders like depression occur or worsen. One recent study looked at the relationship between pain, sleep, and depression, stating that, “In individuals with high pain levels, the combination of poor sleep and pain exacerbated depression.”

In addition to exacerbating existing chronic pain, lack of sleep may actually increase the risk of developing a chronic pain condition, such as fibromyalgia. A study conducted at the Norwegian University of Science and Technology found that women who always or often had trouble sleeping had anywhere from three to five times the risk of fibromyalgia, depending on age. It’s unknown whether lack of sleep actually causes fibromyalgia, but it is clear that the two conditions often go hand in hand.

Health benefits of sleep

Just as not getting enough sleep carries risks, getting plenty of healthy sleep carries benefits.

The cycle of pain and sleep deprivation works in reverse, too. Getting enough healthy sleep will reduce pain and fatigue, which in turn makes it easier to both sleep and exercise (which also helps control chronic pain). In fact, one study found that quality of sleep is the best predictor of physical activity in pain patients. Because of this, focusing on helping pain patients get enough good-quality sleep might be an effective way to lower pain and increase quality of life.

As for other health benefits of getting enough good-quality sleep, consider the risks of sleep deprivation. All those risks are flipped around. Instead of a higher risk of depression or heart disease or pain, an individual who’s sleeping well and for long enough will experience a lowered risk for all these conditions.

To reap the full health benefits of sleep, most adults should get around seven to eight hours. However, this is a generalized guideline. Sleep-deprived individuals will need some extra sleep until they’re caught up. If you feel fatigued after eight hours of sleep, consider sleeping a little longer. Interrupted sleep might also create a need for more nighttime sleep or the occasional daytime nap. If you’re having trouble falling asleep or staying asleep, or feel tired during the day, talk to your physician for advice on improving your sleep health.

How much sleep do you average per night?

Image by Andrew Roberts via Flickr

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