There was a time when no one was really sure why we sleep. Researchers came up with evolutionary theories – stating that sleep is necessary to help us stay out of trouble and keep ourselves safe from animals who hunt after sunset. Some researchers also propounded physiological theories and believed that sleep was essential to conserve energy.
Recent studies, however, have discovered that there is a tonne of other ways in which irregular or lack of sleep can risk you more than just a cranky morning, whether you’re an adult or a child. For one, it can severely damage your brain function.
1. Decreased Memory Power
Throughout the day, your brain makes plenty of connections and learns new things with every passing hour. Not all of these are worth saving though. So sleep is a time when your brain’s synapses consolidate this new information – storing the bits it needs in permanent memory and pruning back the ones that it doesn’t.
Studies show that when learning a certain task and recalling that same task were separated by a night of sleep rather than the same amount of time during waking hours, people recalled information much better.1
Therefore, it is evident that irregular or lack of sleep interrupts your brain’s ability to store vital information, which in turn, affects your learning process.
2. Build Up Of Toxins In The Brain
Research shows that the brain’s lymphatic system opens up at night and flushes out all the toxins while you’re fast asleep. This flushing out of toxins is more rapid, and therefore, far more effective when you’re sleeping than when you’re awake. This is because the space between your brain cells expand dramatically when you’re asleep, thus forcing out all the ‘gunk’ in between through the cerebrospinal fluid.2
Most of this cerebral waste involves a protein called beta-amyloid. Without proper sleep, the brain fails to flush out this protein and allows it to build up over time. Gradually, this protein forms tangles and plaques in between the nerve cells in the brain. This interferes with communication between your brain’s neural cells, leading to poor cognitive function and ultimately increasing your risks of becoming a victim of Alzheimer’s Disease.3
For this reason, disturbed or lack of sleep is so strongly associated with Alzheimer’s Disease. Studies show that levels of beta-amyloid in the brain decrease during sleep while other research suggests that sleep may facilitate the clearance of beta-amyloid by regulating the brain’s glymphatic system.4 5
3. Decreased Cognitive Function
Your brain falls asleep in different stages. A typical night’s sleep of seven or eight hours is made up of five different sleep cycles, each of which lasts for about ninety minutes. The last or the final stage called rapid eye movement (REM) sleep is extremely important in memory formation and cognitive function. During REM sleep, your brain undergoes very high levels of neural activity. This is the stage of sleep that is associated with dreaming, during which flashes of neural impulses are constantly relayed between the spinal cord, brain, and neighboring structures. This is also a phase where blood flow to the brain is at its highest, which further assists in memory consolidation and cognitive function.
People who constantly suffer from disturbed sleep are more likely to have to narrower blood vessels. This decreases the much-needed flow of oxygen-rich blood to the brain, thus affecting its ability to store important information.6 This inevitably leads to cognitive impairment which is characterized by decreased alertness, frequent lapses in attention, slowed responses, and instability during waking hours.7
4. Inability To Regulate Emotions
Disturbed or lack of sleep also makes you focus more on negative emotions, leading you to feel more stressed and angry.8 This emotional volatility may partly be due to the interrupted connection between areas of the brain that process and regulate emotions. A well-rested brain shows a strong communication between the amygdala (the part of the brain that processes your emotions) and the medial prefrontal cortex (the part of the brain that helps regulate feelings). When you sleep less, this communication between these parts of your brain gets disrupted.9 This, along with impaired judgment and decision making skills (due to decreased cognitive function, which is also a result of irregular sleep) makes your mood worse in your wakeful hours, causing you to react violently and unreasonably.
|↑1||Gais, Steffen, Brian Lucas, and Jan Born. “Sleep after learning aids memory recall.” Learning & Memory 13, no. 3 (2006): 259-262.|
|↑2||How Sleep Clears The Brain. National Institutes of Health.|
|↑3||What Happens to the Brain in Alzheimer’s Disease? National Institute of Health.|
|↑4||Cedernaes, Jonathan, Ricardo S. Osorio, Andrew W. Varga, Korey Kam, Helgi B. Schiöth, and Christian Benedict. “Candidate mechanisms underlying the association between sleep-wake disruptions and Alzheimer’s disease.” Sleep medicine reviews 31 (2017): 102-111.|
|↑5||Xie, Lulu, Hongyi Kang, Qiwu Xu, Michael J. Chen, Yonghong Liao, Meenakshisundaram Thiyagarajan, John O’Donnell et al. “Sleep drives metabolite clearance from the adult brain.” science 342, no. 6156 (2013): 373-377.|
|↑6||Too little sleep, and too much, affect memory. Harvard Medical School.|
|↑7||Alhola, Paula, and Päivi Polo-Kantola. “Sleep deprivation: Impact on cognitive performance.” Neuropsychiatric disease and treatment 3, no. 5 (2007): 553.|
|↑8||Sleep and Mood. Harvard Medical School.|
|↑9||Goldstein, Andrea N., and Matthew P. Walker. “The role of sleep in emotional brain function.” Annual review of clinical psychology 10 (2014): 679-708.|