Student Article
Why We Sleep: How Rest Helps Our Body and Brain
Altered (adjective): Changed from the usual or original condition.
Glymphatic (adjective): Related to the system in the brain that clears waste.
Consolidation (noun): The process of strengthening or solidifying something, such as a memory.
Despite leaving us vulnerable, sleep is a complex biological necessity with profound effects on the brain and body.
Sleep isn’t just rest — it’s power for your brain and body
Sleep is a unique state of altered consciousness in which we become less aware of our surroundings, and it’s vital to our survival. Though it varies across species — dolphins, for instance, sleep with one hemisphere of their brain at a time — humans experience a cycle of four distinct stages.
The four stages of sleep
Sleep comes in four main stages:
N1 — light sleep (you’re just starting to drift off)
N2 — deeper sleep with special brain waves
N3 — the deepest sleep, where your body does most of its physical recovery
REM (rapid eye movement) — your brain becomes active, you start dreaming, and your eyes move quickly (even though your body stays still!)
Each full cycle lasts about 90 minutes and repeats several times a night.
How much sleep do you really need?
The amount of sleep we need changes with age. Toddlers require up to 14 hours, teens need about 8-10, and most adults function best with 7-9 hours. While some may claim to thrive on 4-5 hours, research suggests this is rare and can lead to long-term health issues.
In fact, insufficient or excessive sleep is linked to obesity, diabetes, and cardiovascular diseases. It’s unclear whether sleep affects these conditions or if the illnesses themselves disrupt sleep patterns.
What sleep does for you
So why do we sleep at all, especially when it limits activities vital to survival like eating and detecting danger? One theory is energy conservation: by sleeping, we reduce the need for food and keep still during the night when threats may be greater. Another idea is that sleep evolved to promote brain maintenance — like the glymphatic system clearing waste from the brain during rest. Sleep also supports immune health, learning, memory consolidation, and emotional balance.
Sleep may have helped early humans survive
Although sleep makes us less aware of dangers, it may have helped early humans stay safe at night by keeping them still and quiet when predators were around. And dreams, once seen by Freud as expressions of hidden desires, are now thought to help process emotions or simulate real-world challenges.
Sleep is essential!
In essence, although some mysteries remain, modern science confirms that sleep is anything but passive — it’s an active and essential part of life.
© Alice Gregory / Our Media
Altered (adjective): Changed from the usual or original condition.
Glymphatic (adjective): Related to the system in the brain that clears waste.
Consolidation (noun): The process of strengthening or solidifying something, such as a memory.