← Resources Sleep Hygiene
Dr. Kirath Sidhu · ASP Medical
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Interactive Health Education

Sleep Hygiene

You spend a third of your life asleep — or at least you should. Here's the science of why sleep matters, what's sabotaging yours, and how to fix it.

7–9 hrs
Recommended nightly
35%
Adults sleeping <7 hrs
13%
Productivity loss from poor sleep

The Foundation

Why does sleep matter?

Sleep isn't downtime. It's maintenance.

We tend to think of sleep as the part of the day where nothing happens. The truth is the opposite — your brain and body are running critical repair processes that can't happen while you're awake.

Memory consolidation, muscle repair, hormone regulation, immune system maintenance — all of this happens while you sleep. Skip it, and these processes get interrupted.

What happens when you don't sleep enough?

🧠
Cognitive Decline
Concentration, decision-making, and reaction time all drop significantly
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Mood Disruption
Irritability, anxiety, and emotional reactivity increase
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Weakened Immunity
Your body produces fewer infection-fighting antibodies
⚖️
Weight Gain
Poor sleep disrupts leptin and ghrelin — the hormones that control hunger
❤️
Heart Risk
Chronic sleep deprivation raises blood pressure and inflammation
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Workplace Impact
Estimated 13% productivity loss in employees sleeping under 6 hours

How Sleep Works

Your body has a built-in clock

The Circadian Rhythm

Your body runs on a roughly 24-hour internal clock called the circadian rhythm. It controls when you feel alert and when you feel sleepy — and it's primarily driven by light exposure.

When light hits your eyes, it signals your brain to suppress melatonin (the sleep hormone) and increase cortisol (the alertness hormone). When light fades, the reverse happens.

This is why screen light at night is so damaging — your phone is essentially telling your brain it's still daytime.

Sleep Stages

A full sleep cycle takes about 90 minutes and repeats 4–6 times per night. Each cycle moves through distinct stages:

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Stage 1
Light sleep — easy to wake, lasts 5–10 min
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Stage 2
Body temperature drops, heart rate slows
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Stage 3
Deep sleep — tissue repair, immune recovery
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REM
Brain active, dreaming, memory consolidation

Deep sleep dominates the first half of the night. REM dominates the second half. This is why sleeping only 5 hours doesn't give you "half" the benefit — you're losing almost all your REM time.

Sleep Debt — It's Real

If you need 8 hours and only get 6, you accumulate 2 hours of sleep debt per night. By Friday, that's 10 hours. Your body keeps a running tally.

Sleep debt can't be fully repaid by "sleeping in" on weekends. While one or two extra hours help, chronic debt leads to long-term cognitive and metabolic changes that weekend lie-ins can't reverse.

The only real fix is consistent, adequate sleep — night after night.

Environment Matters

Build the perfect sleep environment

Ideal vs Worst Bedroom

Your bedroom environment has a direct, measurable impact on sleep quality. Toggle between the ideal and worst-case scenarios to see the difference across every factor.

🌙 The Perfect Sleep Environment

🕐 How Much Sleep Do You Need?

Enter your age to see the recommendation.

Build Your Routine

Habits that actually work

The Wind-Down — Start 60 Minutes Before Bed

  • 📵 Screens off 60 minutes before bed — or at minimum, enable night mode and reduce brightness
  • 🫖 Switch to a calming activity — reading, light stretching, a warm (non-caffeinated) drink
  • 💡 Dim the lights progressively — signal to your brain that night is coming
  • 📝 Brain dump — write tomorrow's to-do list so your mind can let go

Daytime habits that affect tonight's sleep

  • ☕ No caffeine after 2pm — caffeine has a half-life of 5–6 hours. A 3pm coffee is still 50% active at 9pm
  • 🏃 Exercise — but not too late — regular exercise improves sleep quality, but intense workouts within 2 hours of bedtime can keep you wired
  • ☀️ Get morning sunlight — 10–15 minutes of natural light in the morning anchors your circadian rhythm
  • 🍽️ Avoid heavy meals close to bedtime — digestion raises core body temperature, which works against sleep onset

Consistency is everything

The single most impactful thing you can do for your sleep is go to bed and wake up at the same time every day — including weekends. Your circadian rhythm thrives on predictability.

Even a 30-minute shift in your wake time disrupts your cycle. A consistent schedule trains your body to feel sleepy and alert at the right times, reducing the time it takes to fall asleep and improving overall sleep quality.

If you take away one thing from this presentation: Pick a wake-up time and stick to it — 7 days a week. Your body will adjust your bedtime naturally.

Common sleep myths

❌ Myth
"I can catch up on weekends"
Weekend lie-ins help a little, but they can't reverse the metabolic and cognitive effects of chronic sleep debt. They also shift your circadian rhythm, making Monday mornings harder.
❌ Myth
"Alcohol helps me sleep"
Alcohol helps you fall asleep faster, but it fragments your sleep cycles — particularly REM sleep. You wake up less rested, not more.
❌ Myth
"I only need 5 hours"
Less than 1% of the population genuinely functions well on under 6 hours. The rest are simply used to being sleep-deprived — and don't realise how much better they'd feel with 7–8.
❌ Myth
"Naps make up for lost sleep"
Short naps (15–20 min) help with alertness, but long naps reduce sleep drive and can make it harder to fall asleep at night.

Test Yourself

How much did you learn?
1. What is the ideal bedroom temperature for sleep?
A 16–17°C
B 18–20°C
C 22–24°C
D 25–27°C
Research consistently shows 18–20°C (about 65–68°F) is the optimal range. Your body needs to drop its core temperature slightly to initiate sleep — a cooler room makes this easier.
2. What is the half-life of caffeine?
A 1–2 hours
B 3–4 hours
C 5–6 hours
D 8–10 hours
Caffeine has a half-life of 5–6 hours. That means a coffee at 3pm is still 50% active in your system at 9pm. This is why the recommendation is no caffeine after 2pm.
3. How long is one complete sleep cycle?
A 30 minutes
B 60 minutes
C 90 minutes
D 120 minutes
Each sleep cycle lasts roughly 90 minutes and repeats 4–6 times per night. It moves through light sleep, deep sleep, and REM sleep — each serving a different purpose.