Sleep is one of the most confusing aspects of the human condition. People must shut down and recharge for almost one-third of the day to function properly. Why? What makes sleep such an irremovable part of daily routines? How does it impact recovery from exercise? Let’s take a deep dive into these questions and clarify the importance of sleep.
What Happens During Sleep?
To appreciate the importance of sleep, you first need to understand how it works. The most important lesson is that it has varying degrees of effectiveness. Even if you’re lying in bed for seven to nine hours per night, that doesn’t guarantee you’re getting enough sleep. Quality is more important than quantity.
Rapid eye movement (REM) sleep is the deepest and most beneficial form of rest. Eyes are quite active in this state of unconsciousness as people dream. You must pass through four stages to achieve REM sleep and maximize your recovery:
- Stage 1: Once you fall asleep, your brain activity, heart rate and eye movements slow down. This stage usually lasts less than 10 minutes.
- Stage 2: Your brain waves briefly spike, but then you settle into a deeper sleep as your body continues to relax. This stage makes up the majority of your sleep time.
- Stage 3: Deep sleep begins. Your eyes and muscles remain stationary as your body starts to repair its cells and muscle tissue.
- Stage 4: If you stay asleep for about 90 minutes, you will enter REM sleep and start dreaming. Your heart rate and brain waves speed up and your eyes become hyperactive.
Most physical and mental recovery occurs during the latter two stages. If you keep tossing and turning at night, you’re probably not getting enough REM sleep. Adults must fall and stay asleep for at least seven hours every night to ensure a full recovery.
Why Is Sleep Necessary for Recovery?
Sleep is so important for recovery because it’s the only time when minds and bodies can achieve a state of total relaxation. Other leisure moments also help people recover, but they pale compared to a good night’s sleep. Here are the seven primary ways sleep helps regain strength and maintain athletic performance.
1. Energy Maintenance
Sleep is the body’s primary energy maintenance mechanism. It lowers our metabolic rate, which in turn reduces caloric requirements and helps conserve precious energy. If people stayed awake 24/7, they would have to eat and drink much more often to meet their energy needs. Sleep provides a necessary break from physical activity to balance things out.
According to a study from the Ohio Sleep Medicine and Neuroscience Institute, a solid eight hours of sleep conserves about 35% of energy used during waking hours.
We don’t know much about the evolution of sleep, but we do know why humans prefer to rest at night. The reason is directly connected to energy levels. People are biologically inclined to sleep at night because the darkness makes it less efficient to hunt for food. They can store energy to improve their chances of survival the next day.
2. Cell Restoration
While the brain cleans itself, the rest of the cells in your body repair themselves. Once you enter deep sleep, your nervous system releases anabolic hormones that start the skeletal tissue recovery process. Bodies undergo the all-important protein synthesis that leads to larger, denser and stronger muscles.
Without a good night’s sleep, bodies release catabolic hormones instead of anabolic hormones. Catabolic hormones — namely cortisol — get released when nervous systems are overstimulated and need an extra energy boost to function. These hormones then convert amino acids into adenosine triphosphate (ATP), which interferes with muscle recovery.
Other forms of physical therapy can also repair muscle tissue, such as ice baths and deep tissue massages. However, bodies are still active, so recovery isn’t nearly as effective. Sleep relaxes the whole body and allows the cells to devote 100% of their energy to reproduction and tissue growth.
Sleep allows you to enter an intense anabolic state and maximize cell restoration. A lack of sleep traps you in a catabolic state, which prevents your cells from fully recovering. A consistent sleep schedule is nonnegotiable if you’re trying to gain muscle.
However, sleep can be detrimental to your muscle growth in cases of poor sleep posture. Sleeping in uncomfortable positions usually results in temporary soreness, but sometimes it causes lasting injuries or mobility issues that limit your athletic performance. Ensure you’re sleeping with proper body alignment to ensure complete muscle recovery.
3. Cognitive Function
Neurological activity might slow down during sleep, but the brain still has an important job to do. The brain’s glymphatic system removes waste from the central nervous system in deep sleep. This primarily consists of leftover proteins that float around in the brain cavity and can prevent it from functioning properly.
Brain waste builds up throughout the day as neurons consume energy. Sleep settles bodies down and gives the glymphatic system a chance to clean up. Discarding brain waste improves mental performance, including memory, concentration and problem-solving skills. Brains would be in a permanent state of fogginess without sleep.
Sleep’s cognitive benefits are also apparent in students’ academic performance. Kids who get close to eight hours of sleep perform much better in school than their deprived counterparts. That’s why you should always focus on rest the night before a big exam instead of staying up late to study.
4. Emotional Stability
Aside from physical exhaustion, emotional instability is the most obvious side effect of poor sleeping habits. People become grumpy, irrational and more prone to mood swings. During sleep, brain activity increases in a few specific areas responsible for controlling emotions:
- Hypothalamus: This area is the primary emotional response control system. It’s also in charge of releasing hormones and maintaining body temperature.
- Hippocampus. The hippocampus stores memories. It helps people memorize their environments and maintain spatial awareness, keeping emotions in check.
- Amygdala: The amygdala coordinates emotional responses to new stimuli, primarily triggering fear and anger when threats emerge.
- Limbic cortex. This cortex consists of the cingulate and parahippocampal gyrus, which impact moods and decision-making skills.
A consistent sleep schedule allows these essential brain components to regulate your emotions and prevent overreactions. That way, you can better focus on your workout routine or sport.
5. Weight Management
It’s natural if you don’t always feel hungry in the morning. Sleep stifles the hunger hormone ghrelin to prevent hunger from waking you up. It also releases more leptin, which causes the “full” sensation after eating. These hormones also change their activity because you’re using less energy, which means food isn’t an immediate necessity.
Sleep also stabilizes your insulin levels. Insulin is the hormone that converts glucose into energy. Without it, people would develop high glucose levels and soon become diabetic. Proper insulin function is crucial for overall health. Sleep keeps cells healthy so they can absorb glucose for fuel.
Getting enough sleep helps you prevent obesity and lowers your chances of developing chronic health issues, such as metabolic syndrome and weight-related arthritis. If you’re trying to lose or control weight, ensure your sleep schedule is on point and you maintain your fitness routine.
6. Cardiovascular Health
Sleep also supports your cardiovascular health. Staying at a healthy weight drastically reduces your risk of developing heart disease and stabilizes your blood pressure.
Your cardiovascular system also takes a much-needed break as you sleep. Your heart, arteries and veins aren’t designed to operate on a resting heart rate of 80+ beats per minute. Sleep lowers it to a more manageable 40-60 BPM. At this rate, your body can regulate its blood glucose levels more easily and thus speed up energy regeneration.
Immune systems need sleep to function at 100%. Many studies have shown a close correlation between sleep deprivation and higher susceptibility to illness among all age groups. These findings shouldn’t be surprising. When you have low energy, poor brain function and deteriorating cell health, sickness usually isn’t far behind.
Sleep strengthens immune systems by producing antibodies and cytokines — the main proteins fighting viral infections and inflammation. It also makes an indirect impact by enabling white blood cells and platelets to reproduce more quickly. These cells are the main forces that identify and destroy bodily contagions.
The old saying “sleep is the best medicine” is scientifically correct when it comes to most minor illnesses. The need for sleep increases when people contract a virus and start showing symptoms. The body needs more immune cells to fight back the disease. That’s why flu and fever often come with a state of perpetual exhaustion. Your body is telling you to rest.
Sleep Is the Key to Success
There’s a good reason people devote most of their lives to sleeping. It’s an irrevocable aspect of overall health. Without it, you would see a sharp decline in your physical, mental and emotional functions. Your immune system would weaken and energy levels would be inconsistent. Sleep is the key to success in any life endeavor, whether athletic, educational or recreational. Use it to your advantage to help you stay in peak physical condition.