Sleep Deprivation and Its Effects on the Brain
For many students, lack of sleep or pulling an all-nighter is a familiar act. But how does this affect our brains, and what are the consequences of it?
Sleep deprivation is caused by a consistent lack of sleep or reduced quality of sleep. For most people, the recommended amount of sleep needed for best health is 7 to 8 hours each night. Receiving less than this for a prolonged period of time can lead to many health issues, such as an increased risk for heart disease, diabetes, stroke, and irregular heartbeat. More importantly, sleep plays a vital role in learning, memory, emotions, and cognitive function.
When you are asleep, your brain cycles between two types of sleep: REM and non-REM. Non-REM sleep is composed of three stages and is the first part of the cycle. During this, your brain waves begin to slow along with your heartbeat, breathing, and eye movements. In REM sleep, your brain frequencies increase to an awake state, and most dreaming occurs here. While you are sleeping, your body will cycle between non-REM and REM, typically four or five times a night.
Brain electrical activity during non-REM (NREM) and REM sleep via EEG (Lumen Learning).
During sleep, our body conserves energy, performs cellular restoration, controls hormones, and supports heart health. In addition, the brain undergoes waste disposal via the glymphatic system. This is thought to be a network of vessels in the scalp that drains cerebrospinal fluid. The products that are cleared include clumps of misfolded proteins— including ones that can lead to neurodegenerative diseases like Alzheimer’s. Since the glymphatic system works best when we are asleep, sleep disturbances reduce the efficiency of the brain’s waste disposal system, thus increasing the likelihood of neurological disease.
Cerebral brain waste removal during sleep (Boston University).
Mental Health and Emotion
Sleep deprivation can boost activity in the brain’s emotional centers. Not only does this increase risky behaviour, but it can also lead to mental illnesses. In a study conducted by the University of California Berkeley, it was found that the emotional center of the brain was increased by 60%. Mental health and sleep have an interdependent relationship. Poor quality of either will result in a negative effect on the other. For example, many people suffering from depression also show symptoms of insomnia. In the same manner, poor sleep is associated with the exacerbation of depression. Many other mental illnesses such as bipolar disorder, anxiety, and schizophrenia have similar cases to this.
Reduced cognitive function and sluggish behaviour from sleep deprivation are due to attentional lapses and brief moments of inattentiveness. These lapses are caused by microsleeps—very short periods of sleep-like EEG activity that occur while the brain is still awake and running. Unlike usual rapid reaction, neuron response is slower, fires weaker, and has longer transmission rates. Experiments have shown that sleep deprivation selectively affects certain areas of the brain, such as the prefrontal cortex. The prefrontal cortex is responsible for cognitive functions like higher functions, language, divergent thinking, creativity, and executive decisions. This targeted response also affects memory and attention. The executive process of memory and attention is found in the frontal lobe. Since this area is vulnerable to sleep deprivation, memory and attention are impaired.
Diagram of the brain: the prefrontal cortex is the cerebral cortex covering the front part of the frontal lobe (TheMantic Education).
In addition to the previous cognitive functions, sleep deprivation is linked to slower visual input encoding and translation. It increases rigid thinking, difficulty using new information, and deterioration in decision-making.
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Featured image is courtesy of National Public Radio.
Article Author: Jennifer Law
Article Editors: Valerie Shirobokov, Victoria Huang