What are the mental and physical health benefits of sleep? How does sleep affect your mental well-being?
Shawn Stevenson says that sleep is a vital process that allows your mind and body to rest and rejuvenate. Sleep affects almost every aspect of your overall health, including your daily energy levels, long-term cardiovascular health, and mental health.
Let’s look at some of the ways sleep impacts your body and brain.
The Importance of Sleep for the Body
Stevenson asserts that when you sleep, various processes happen within you that give you the health benefits of sleep. Sleep is an anabolic state, meaning it aids in your body’s natural growth and repair processes of your muscular, immune, and skeletal systems. Without adequate quality sleep, these repair mechanisms don’t work properly. Additionally, sleep keeps your hormone levels balanced and improves your metabolism.
(Shortform note: Stevenson’s emphasis on the importance of sleep for bodily repair and maintenance aligns with research showing that both insufficient and excessive sleep can lead to increased inflammation in the body. As such, disruptions in sleep patterns might not only hinder beneficial processes but potentially lead to harmful inflammatory responses. Chronic inflammation in your body can hinder your immune system and damage healthy cells and tissues. This can result in chronic illnesses and other health problems.)
Beyond its generally negative effects on everyday health, sleep deprivation has larger, long-term implications for your health. Research indicates that not getting enough sleep puts you at greater risk of heart disease.
(Shortform note: In Why We Sleep, Matthew Walker explains why sleep deprivation may increase the risk of cardiovascular disease: It activates the sympathetic nervous system, which leads to increased heart rate, blood pressure, cortisol (stress hormone), and atherosclerosis (especially of coronary arteries). Through hormone signaling, sleep deprivation also decreases HDL (good cholesterol) and growth hormone (which promotes recovery of blood vessel endothelium).)
Further, writes Stevenson, sleep deprivation can lead you to develop insulin resistance at the same level as a person with type 2 diabetes. When you’re insulin resistant, your body ages faster, and you build up more fat.
(Shortform note: A recent study supports the link between sleep deprivation and insulin resistance, finding that obese people who are night owls (those who are more active at night) have a 37% risk of type 2 diabetes—significantly higher than the 9% risk for morning larks (early risers).)
The Benefits of Sleep for the Brain
Stevenson writes that in addition to its effect on the health of your body as a whole, sleep strongly impacts the health of your brain. Human brains are incredibly complex, and the various functions they serve while we’re awake produce waste products. These waste products, along with toxins and dead cells, need to be removed for your brain to stay healthy.
Sleep enables this waste removal. While you’re sleeping, your glymphatic system—the brain’s waste removal system—is 10 times more active than it is when you’re awake. Additionally, your brain cells shrink by about 60% during sleep, allowing the tidying-up process to become more efficient. When you don’t get enough quality sleep, your brain doesn’t have the chance to complete this process, and the waste products stay in your brain. Over time, this can have serious consequences, including the development of Alzheimer’s disease.
(Shortform note: The research Stevenson relies on for his statistics about the brain’s nightly cleaning routine has implications for cognitive diseases like Alzheimer’s. Some studies highlight that critical molecules associated with Alzheimer’s—beta-amyloid (Aß) and tau—are removed during the cleaning cycle. Even a single night of sleep deprivation can lead to a surge in these harmful molecules in memory-processing regions of our brains like the thalamus and hippocampus. Furthermore, lifestyle factors affecting sleep such as shift work or sedentary habits can hinder this cleaning process, leading to decreased glymphatic activity.)
