Most people are under the impression that the brain and body shut down when we sleep, but this is not the case. When we sleep, our bodies get the chance to reset and heal while the brain sorts out information and memories. There are actually many processes that occur as we sleep, and they are organized in sleep cycles. These are stages of sleep that we go through each and every night.
The Sleep Foundation explains that sleep is “an essential function that allows your body and mind to recharge'' (2020). But, why is healthy sleep so important and how does a good night’s rest affect your health? One thing’s for sure, when we sleep well, we feel better, and we perform better the following day, so it is useful to know how sleep impacts our lives.
How Does Sleep Affect Your Health?
Healthy sleep involves more than just getting in your 8 hours a night. A good night sleep includes quality sleep, spending the right amount of time in each of the sleep stages, and listening to your internal clock. A good night’s sleep will impact your brain function and your physical health. Consider the areas in which sleep affects your health:
Lack of sleep results in weight gain and even obesity. Studies show a significant link between weight gain in young adults and short sleep duration. Various studies have backed up this claim. According to this study, people who haven’t had enough sleep tend to consume more calories than those who have sufficient rest. Short sleep is directly connected to increased appetite, and as a result, higher body mass index (BMI).
Healthy and strong heart
During sleep, your blood pressure lowers, giving your blood vessels and heart a bit of rest. Lack of rest can result in high blood pressure, which can cause stroke or heart attack. Studies show that heart attacks and strokes are more likely to happen in the morning hours because of how sleep links with the blood vessels. Sufficient sleep is necessary for better heart health.
Sleep deprivation leads to a weakened immune system. Your immune system works by fighting off any viruses and bacteria. Lack of sleep leads to lagging and prevents your body from fighting off harmful infections. You’ll end up staying in bed recovering from illnesses. If you get the flu or a cold often, you should check your sleep quality.
Sufficient quality rest is integral to your mental health. Sleep loss could cause you to be moody, quick-tempered, and emotional. If sleep deprivation persists, it often leads to depression and anxiety. Surveys show that most people suffering from depression and anxiety sleep less than six hours a night, which is unhealthy. Researchers explain, “In clinical samples, difficulty in initiating or maintaining sleep (including early morning waking) or both, have been reported in about three quarters of all depressed patients” (Nutt, et al. 2008). There has been extensive research and documentation of the link between disturbed sleep habits and depression.
A study conducted on collegiate basketball players showed that sufficient sleep resulted in a peak in athletic performance. Insufficient sleep negatively affected the athlete’s performance. Poor sleep robs you of muscle recovery time, energy, and motivation.
Insufficient sleep prevents you from being alert and affects your creative thinking and problem-solving abilities. Sleep allows your neurons to reorganize and your brain rids itself of toxic by-products that have built up throughout the day. Sleep helps with memory, too, as it rids unnecessary information that could clutter your nervous system while retaining critical information. For this process to take place, you need to spend time in deep sleep.
The Sleep Stages
To understand why sleep is so important for your brain, body, and overall health, it is important to understand the sleep cycle. The two types of sleep include REM (rapid eye movement) and non-REM. You cycle between these two stages of sleep multiple times throughout the night.
Non-REM is the phase of sleep which occurs before the REM stage. It accounts for 75-80% of a healthy adult’s sleep. There are three stages of non-REM:
- Stage 1: This occurs right after you fall asleep and is typically very short (approximately 10 minutes). In this stage you are in a very light sleep and can be woken up easily.
- Stage 2: Stage 2 lasts between 30 and 60 minutes. In this time, your muscles become more relaxed and you will begin to have some brain activity.
- Stage 3: In the final stage of non-REM sleep you will have increased brain activity and potentially have some body movements. It is very difficult to wake someone up in this 20-40 minute stage.
The REM cycle typically begins 90 minutes after falling asleep and accounts for about 20-25% of an average adult’s sleep schedule. During the REM sleep stage the brain is almost as active as it is when you are awake. It is named for the way in which your eyes move back and forth during this stage of sleep. Many things occur during the REM stage:
- Fast or irregular breathing
- Increased heart rate and blood pressure
- Twitching of the face and limbs
- Increased oxygen consumption of the brain
- Changes in body temperature
- Dreaming and memory formation
On any given night, this cycle is repeated 3 to 4 times, with more time spent in the non-REM cycle than the REM cycle. So, what is actually happening when you are asleep?
What happens when we are asleep?
Now that you know the areas of your life that are impacted by sleep and the sleep stages that you cycle through each night, you might be interested in what happens during sleep.
- The brain gets to work. It sorts out all the day’s information and chooses what memories should be kept and what isn’t that important. That’s how we store long-term memory.
- Your body releases hormones. When the sun goes down, the pineal gland receives the signal to release melatonin. Melatonin levels are high at night, which makes you sleepy. Additionally, your pituitary gland produces a growth hormone that helps your body grow and repair itself.
- Decrease in stress hormones. In the first half of the night, once your body rests in sleep, your cortisol levels, also known as stress hormones, go down, especially in the first half of the night. When you wake up, the hormone levels increase significantly, which helps with your appetite and makes you feel perky and energetic.
- The Sympathetic Nervous System rests. When you haven’t had enough sleep, your fight or flight mode kicks in, which could also result in coronary heart disease. Studies have shown that lack of good sleep could increase blood pressure and sympathetic nervous system activity.
Can One Have Too Much Sleep?
The short answer is Yes! While insufficient sleep is more common, it is also possible to sleep too much. Too much sleep is also known as hypersomnia. People who suffer from hypersomnia experience excessive sleepiness when they’re supposed to be productive. Hypersomnia is a result of spending too much of your sleep in non-REM and less time in deep sleep. It affects your sleep quality.
It is unhealthy to sleep more than nine hours a night as an adult. Sleeping more than necessary causes a build-up in calcium in the arteries, leg arteries, and heart. Seven to eight hours of sleep is sufficient and should allow you to have an energized, productive day. Hypersomnia also affects your mental health. In fact, “hypersomnia is present in about 40% of young depressed adults and 10% of older patients” (Nutt, et al. 2008).
Sleep is a necessary tool for both physical and mental well-being. While all the stages of sleep are essential, deep sleep is vital for you to feel rested and stay healthy. Taking care of your sleep could help you improve your mental and physical health tremendously. For advice on how to get better, more restful sleep, visit the Mayo Clinic.
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