The Science of Sleep

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Reporter: Modeline Longjohn

The oxford dictionary defines sleep as a condition of body and mind which typically keeps recurring for several hours every night. It is when the nervous system is inactive, the eyes closed, the postural muscles relaxed, and consciousness is practically suspended. This concise definition wraps up a web of intricate scientific mechanisms in a few words, which both do justice to the point and belie its true depth.

Every time you close your eyes in preparation for sleep (be it a short nap, a well deserved night’s rest, or the student version – the only thing to do when your body has had enough of studying and coursework), a set of chain reactions is triggered. These reactions create positive or negative feedback systems, depending on your pre- sleep actions. Pre-sleep actions are any activities done right before sleep including but not limited to having a meal, consumption of sleep-inducing tea, switching from bright to dim lights (in the bedroom) and switching to sleep mode of gadgets. Positive feedback process culminates in sleep, while negative feedback process prolongs the time it takes to fall asleep or, in some cases, induces complete inability to sleep, commonly known as insomnia.

Sleep is regulated by two closely interacting mechanisms called the circadian rhythm and sleep-wake homeostasis respectively. The circadian rhythm is the body’s internal/biological clock and alertness maintenance system while sleep-wake homeostasis is the sum total of chemical substances within the body which interacts to induce a balancing sleep drive. The internal body clock, named after the animals they were first discovered in called Cicadas, is based in the hypothalamus of the brain from where it regulates the body’s sleep timing based on day-night/light-dark cycle. Furthermore, alertness signals for wakefulness and switching between rapid eye movement (REM) and non-REM sleep are neurological processes that occur while a person is fast asleep. It should be noted that REM sleep is the more beneficial sleep type (for renewing and rejuvenate body and brain activity) and can be altered by consumption of stimulants like alcohol, sleeping medication, caffeine, nicotine and amphetamines.

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In a nutshell, the brain regulates sleep based on light (day)/dark (night) pattern in sync with brain activity/rhythm, body temperature, thirst and hunger pangs, hormone secretion levels and most other biological processes. The circadian rhythm works in tandem with the body’s internal biochemical system (the sleep/wake homeostasis) which stimulates an urge to sleep in addition to regulating sleep intensity using chemicals including melatonin. This urge to sleep slowly surges and peaks when a person falls asleep and slowly declines until wakefulness is achieved. So next time you close your eyes to sleep, take a minute to think about the underlying scientific mechanisms most of which sleep scientists continually research to unravel.

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