IN A WORLD THAT worships productivity, sleep has become the poor intern of human biology—overworked, underpaid and blamed for everything. If you sleep eight hours, people look at you with suspicion, as if you have confessed to fraud. “Eight hours?” they ask. “What a luxury!” And then they proudly tell you that they sleep five, as though exhaustion were a competitive sport.
But the brain, that quiet tyrant inside our skull, does not care about cultural bravado. It has its own night shift. And it begins the moment we close our eyes.
Sleep happens in stages. Four of them, to be exact.
Stage N1, the lightest stage, is that delicious moment when the world begins to blur and your thoughts loosen their tie. This is when you see strange fragments of imagery that feel real but make no sense. A flying autorickshaw. A friend from school who now has a horse’s head. A dosa that folds itself. These are called hypnagogic hallucinations, and the brain treats them like a warm-up act before the main performance.
In N2, the cortex begins to file the day away. Small electrical bursts called sleep spindles spark across the brain as though reorganising your memories, much like a librarian with mild OCD. Your heart rate slows. Your body softens. If someone wakes you up at this point, you will insist you were not asleep, but your face will betray you.
Stage N3 is the deep sleep stage, what we doctors call slow wave sleep. This is when your thalamus, the relay station of the brain, goes mostly offline. Your cortex enters a rhythmic hum, almost musical in its regularity. This is the sleep that heals your tissues, repairs your bones, balances your hormones, and strengthens your immunity. If you skip this stage, you do not bounce back. You crumble in slow motion.
And then comes REM sleep, the most dramatic of them all. This is where the amygdala, the seat of emotion, becomes more active than when you are awake. Your cortex lights up as though it is hosting a midnight festival. Your body becomes temporarily paralysed so that you do not flail about acting out your dreams (which, for some people, is very considerate).
REM is where dreams stretch into vivid cinema. It is where your brain stress-tests your emotions, rehearses scenarios, processes grief, and sometimes gifts you the plot of a story you forget seconds after waking.
There is a theory called the threat simulation hypothesis that says dreams help you rehearse fear in a safe environment. This explains why so many people dream about missing flights, losing passwords, or being chased by a giant samosa.
The deeper truth is this: Sleep is not optional. It is not vanity. It is not indulgence. It is biology at its strictest.
When you cut down on sleep, you are not reclaiming time. You are borrowing it and paying it back with interest: irritability, poor judgment, blood pressure problems, weight gain, memory lapses and, in extreme cases, hallucinations. I once had a patient who had not slept for three days. He said he saw his neighbour turning into a crow. I told him to sleep first and complain later.
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Sleep is also the only time your brain takes out the trash. A system called the glymphatic pathway washes away metabolic waste. These are proteins that accumulate during the day and, if left uncleared for years, can contribute to cognitive decline. No amount of antioxidants can compensate for what a long, deep sleep can do in two hours.
Somewhere, we forgot that sleep is our oldest companion. It kept our ancestors alive long before caffeine was invented. It is the quiet friend who repairs what life frays. So, if someone calls you lazy for sleeping eight hours, tell them that your thalamus, amygdala, cortex, hormones, muscles, heart and immune system disagree. Tell them your brain is working harder asleep than when you are awake. And then, politely, go back to bed.
The writer is consultant neurosurgeon, Wockhardt Hospital, Mumbai.