Sleep
Written by Jerry Lau and Tommy Li
It's a Friday night. You just got back from a two am night out with your friends, and as you stumble into your bed, you wonder, how messed up am I going to be tomorrow? Sleep is an integral part of our health. However, with modern American society promoting the culture of excessive work habits, partying hard late into the night, and pulling all-nighters to study for exams, one can only wonder what these collective habits have on our health.
What exactly is sleep, and how do humans fall asleep? Essentially, sleep is a period of rest that the body utilizes as a "housekeeping" phase to remove toxins in the brain that build up while awake. As we prepare to sleep, clusters of sleep-promoting neurons in many parts of the brain become active, and neurotransmitters dampen the activity of cells that play a role in arousal or relaxation (4).
The CDC recommends that adults have a minimum of seven hours of sleep at night, and those seven hours should be "good-quality" sleep. Good-quality rest can be quantitatively based on four factors: sleep latency, sleep-waking, wakefulness, and sleep efficiency. Sleep latency is the measurement of how long it takes to fall asleep (the goal here should be 30 minutes or less); sleep-waking is how often you wake up during your sleep session (the goal here should be once or less); wakefulness is how many minutes you spend awake after you first go to sleep (the goal here should be twenty minutes or less); sleep efficiency is the amount of time you spend sleeping in bed (the goal here should be 85% or more). These four factors contribute to the overall sense of your sleep being "good"; you improve your sleep quality by improving these four factors (3).
Sleep also benefits the retention of memory by protecting them from interfering stimuli and consolidating them. The rapid-eye movement or REM sleep is crucial to memory consolidation and metabolic electrophysiological, neurochemical, and genetic mechanisms inside our body. The brain needs a perfect time to settle down the memory consolidation process and enhance it. A minimum standard of proper sleep is necessary to activate slow-wave rest, stabilizing transformed memories and integrating them into long-term memories. Sleep-deprived adolescents are more likely to incorporate misleading memories of past events. Multiple nights of restricted sleep increase false memory formation and is not recommended. Young adults require more sleep hours to avoid abstract eyewitness testimony (2).
Moreover, growing evidence indicates that short sleep duration and poor sleep habits are associated with the onset and development of chronic diseases or illnesses, acute infections, and premature mortality. A lack of sleep can signal immune parameters critical to our resistance to the outside environment. Our T cell proliferation decreases, which means our T helper cell cytokine responses will be lowered (5). Our natural killer cell will respond slower, and activation of proinflammatory pathways increases. For example, sleep can strengthen your immune system to fight against the possible common cold. The Oxford academic journal "Sleep" suggests that those sleeping > 7 hours per night were associated with a lower risk of the common cold. A lack of sleep may lead to an increased susceptibility to the common cold.
Sleep is essential, and while our culture may promote the productiveness of not sleeping, it is cognizant to realize the many detrimental effects not sleeping will have on your body.
References:
(1) Hirshkowitz M, Whiton K, Albert SM, Alessi C, Bruni O, et al. The National Sleep Foundation’s sleep time duration recommendations: methodology and results summary. Sleep Health. 2015;1(1):40–43.
(2) Lo, J, Chong, P, Ganesan S, et al. Sleep Deprivation Increases Formation of False Memory. Journal of Sleep Research. July 5, 2016.
(3) “What is Sleep Quality?” Sleep and You. National Sleep Foundation. https://www.thensf.org/what-is-sleep-quality/. Accessed 2021 Aug 27.
(4) “Brain Basics: Understanding Sleep.” Patient and Caregiver Education. NIH. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep. Accessed 2021 Aug 27.
(5) Aric A. Prather, PhD, Denise Janicki-Deverts, PhD, Martica H. Hall, PhD, Sheldon Cohen, PhD, Behaviorally Assessed Sleep and Susceptibility to the Common Cold, Sleep, Volume 38, Issue 9, September 2015, Pages 1353–1359.
