A sleep reference
Straight answers about sleep, backed by evidence.
SleepUncovered is the sleep resource the internet doesn't have. Every page answers the question in the first sentence and shows the evidence behind it. No wellness fluff. No affiliate-driven supplement rankings. No “ten tips for better sleep.”
- Topics covered
- 80+
- Calculators
- 10
- Studies cited
- 200+
Start here
The basics, in the right order
01 · Basics
How much sleep do adults actually need
Most healthy adults need 7–9 hours. Sleep need is individual — and chronically getting less than 6 has measurable consequences.
02 · Basics
What happens to your body during sleep
Sleep is a structured biological process — not passive rest. Hormones, memory and immune function all depend on what happens overnight.
03 · Basics
Sleep stages explained — REM, light, deep
You cycle through stages roughly every 90 minutes. Deep sleep dominates early in the night; REM dominates later.
04 · Basics
Circadian rhythm, explained simply
A roughly 24-hour internal clock, set by light and meal timing, that decides when you feel sleepy or alert.
Most common questions
People come here asking these
I can't fall asleep — what's actually happening?
Strong evidenceI wake up tired even after 8 hours.
Moderate evidenceI wake up at 3am and can't get back to sleep.
Moderate evidenceDoes melatonin actually work?
Moderate evidenceIs blue light really keeping me awake?
Limited evidenceWhat is CBT-I and why is it the gold standard?
Strong evidence
Calculators
Tools that do the maths so you don’t
Sleep Cycle Calculator
Wake at the end of a cycle, not the middle.
Caffeine Half-Life Calculator
How much caffeine is still in your system at bedtime.
Chronotype Quiz
Validated MEQ-style — find your natural window.
Sleep Debt Calculator
How much you owe, and how long to repay it.
Jet Lag Calculator
Light exposure schedule for your route.
Room Temperature Checker
Against the 16–19°C optimal sleep range.
From the research
The studies behind the answers
- Strong evidence2003
Van Dongen et al — cumulative cost of sleep restriction
Two weeks of 6-hour nights produced cognitive deficits equal to 24 hours of total sleep deprivation — and participants didn’t notice.
- Strong evidence2017
Walker — sleep deprivation and immune function
One short night reduced natural killer cell activity by 70%. The effect is dose-responsive — less sleep, less immune capacity.
- Strong evidence2009
Morin et al — CBT-I vs medication for chronic insomnia
CBT-I matched or beat zolpidem at six weeks — and held up at 12 months while medication effects didn’t.
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