Research On Sleep And Why It's So Important

Outside of the research-based effects of sleep, individuals may understand that sleep is important. Adverse emotional and physical symptoms can occur when people don’t get adequate sleep. Those who have worked a night shift, pulled an all-nighter, or experienced a sleep disorder like obstructive sleep apnea may know the impacts of going a night or more without getting restorative sleep. In addition, individuals may understand that being well-rested can lead to a sense of being ready to face the day.

Scientists have spent significant resources researching sleep and have discovered that it plays a vital role in many body functions, including memory, immune function, learning, and mental health. Exploring these statistics can help individuals understand even further how sleep’s role in life can impact them personally, as well as ways to improve sleep and find support. 

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Theories about why people sleep

Scientists have come up with multiple theories about why people sleep, including the following. 

Inactive theory

The inactive theory, also called evolutionary or adaptive theory, is one of the earliest theories about sleep. It suggests that being inactive at night served a survival function by keeping living creatures safe when they were particularly vulnerable. Animals that can stay still and quiet at night have an advantage over animals that are active. For example, in the past, predators were more likely to attack animals that were awake, active, and drawing attention to themselves than those who were still and quiet. The theory suggests that, through natural selection, this behavioral strategy evolved into what people now know as sleep. 

This theory has been debunked, with some counterarguments pointing out that there is no advantage to being unconscious and asleep if safety is the goal because it prevents organisms from being able to react in an emergency.

Energy conservation theory

The energy conversation theory about why people sleep suggests that sleep’s primary purpose is to reduce energy demand for part of the day. While this factor may not seem applicable in the modern age, when human ancestors were hunting, gathering, and farming for all their food, conserving energy was a way to utilize limited resources effectively. Some scientists believe this theory to be tied to the inactive theory as both can be connected to survival on a fundamental level. 

Restorative theories

Restorative theories are based on the long-held idea that sleep restores what the body loses when people are awake, allowing the body to repair and rejuvenate. Sleep research has supported this idea over the years. For example, studies have found that animals that are deprived of sleep lose autoimmune function and die in a matter of weeks.

Synaptic homeostasis theory

Another theory about why people sleep is the synaptic homeostasis theory, which proposes that sleep is essential to reducing synapses in the brain. Based on this theory, daily activity increases the number of synapses in the brain, and the brain might become overcrowded if allowed to accumulate synapses continuously. Sleeping allows the brain to prune away unnecessary synapses and strengthen essential ones.

Brain plasticity theory

The brain plasticity theory is a more recent theory that suggests that sleep is correlated with changes in the organization and structure of the brain. The concept of brain plasticity is not well understood. Still, sleep is understood as crucial for brain development in infants and young children, and sleep deprivation can affect an adult’s ability to learn and perform tasks. 

What happens during sleep

The above theories remain unproven, but scientists have been interested in sleep for years, wondering why humans sleep and how sleep affects the body. Their insights have led to understanding the processes that occur during sleep. Sleep affects multiple systems in the body, including the heart and circulatory system, immune system, metabolism, and hormones.

Circulatory system 

When you enter non-rapid eye movement or restorative sleep, your heart rate and blood pressure drop, and your heart does not work as hard as when awake. During REM sleep and when you wake up, your blood pressure and heart rate increase to the usual levels when awake but relaxed.

When people get insufficient sleep at night, their hearts don’t get these periods of rest. People who do not get enough sleep or who wake often throughout the night may have a higher risk of cardiovascular disease, high blood pressure, stroke, obesity, and coronary artery disease. 

Immune system

A lack of sleep can affect the immune system. Studies show that people with short sleep duration or poor-quality sleep are more likely to get sick, and a lack of sleep can affect how long it takes to recover after an illness. 

The immune system releases cytokines during sleep. These proteins have multiple functions and increase during periods of illness or stress. When someone doesn’t get enough sleep, they may not produce enough protective cytokines or other cells and antibodies that fight infection.

Metabolism

How the body processes fat may be related to sleep and the circadian rhythm. Eating and sleeping at irregular times can affect how the body handles fat. Studies have shown that people who do not get enough quality sleep may experience increased hunger, decreased physical activity, metabolic syndrome, and increased consumption of sweet, fatty, or salty foods.

Hormones

The body makes different hormones at different times of day, and when they are produced, they may be related to the circadian rhythm. In the morning, your body releases hormones like cortisol, which promote alertness. A lack of sleep can interrupt the secretion of ghrelin and leptin, the hunger hormones, which can cause people to binge eat during waking hours. Growth hormones surge during sleep, which is essential for muscle growth, maintaining standard body structure, and supporting metabolism.

The brain

Researchers believe that sleep's rejuvenating aspects are specific to cognitive function and the brain. The glymphatic system, a drainage pathway in the brain, clears substances and toxins from the brain and performs more efficiently during sleep. Sleep maintains certain pathways in the brain that allow individuals to create new memories and learn new skills or topics. 

Mental health

Not getting enough sleep or getting poor sleep can increase the risk for some mental health disorders. Insomnia can be a factor in some psychiatric disorders, like depression and anxiety, and a lack of sleep can elicit symptoms of these conditions in otherwise healthy people. People with mental health disorders may be more likely to experience chronic sleep problems, and those sleep problems can exacerbate symptoms, possibly increasing suicide risk. 

How to improve sleep quality

There are many steps individuals can take to improve sleep quality, including but not limited to the following: 

• Instead of lying in bed for a long time, try getting up and partaking in a calming activity like reading for some time and then returning to bed. 
• Stay away from bright lights while you are awake, as it can incite you to stay awake. Turn off the lights in your room. Consider a dim lamp or a night light if you don't like the dark. 
• Don’t nap during the day to ensure you’re tired at bedtime.
• Maintain a bedtime routine where you go to bed and wake up at the same time every day, even on the weekends. 
• Refrain from excessive exercise for at least four hours before bedtime.
• Establish sleep rituals to remind your body that it is time to get ready to fall asleep.
• Use your bed only for sleeping and sex. Don’t watch TV, eat, or work in bed.
• Avoid nicotine, substances, caffeine, and alcohol for four to six hours before bed. 
• Take a hot shower or bath before bed.
• Keep your bedroom comfortable and quiet. If the light from outside bothers you, try blackout curtains or use white noise to drown out other sounds that may prevent you from falling asleep. 
• Avoid blue light from devices. Do not use screens with blue light for at least two hours before bed. If you want to use your devices, you might use a blue-light-blocking filter or glasses. 

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Support options 

If you are having trouble getting enough sleep, you might consider working with a therapist. Cognitive-behavioral therapy (CBT) can effectively treat long-term sleep problems like insomnia and other sleep disorders. This modality can help you identify and manage negative thoughts and worries that may keep you awake and teach positive sleep habits and hygiene techniques. 

Online therapy may be a convenient and flexible option if you face barriers to in-person therapy, such as time, distance, or finances. With an online platform like BetterHelp, you can work with a qualified, licensed professional from the comfort of your home at a time that suits your schedule. In addition, online platforms allow you to use journaling prompts, worksheets, and support groups, which you might not have access to in a traditional face-to-face setting. 

Research has found that online therapy is also effective. One review of 17 studies found that online CBT may be more effective than in-person treatment in some cases and that study participants were equally as satisfied with either type of CBT. This review also found that online CBT was a more cost-effective option.