Free Tool

Sleep QualityEstimator

20 questions about your sleep habits, environment, and how you feel during the day. Get your sleep score, see what's hurting your sleep, and get science-backed fixes.

Free Forever No Sign-up 20 Questions Sleep Score Sleep Debt Calc

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Category Breakdown

Your Personalised Sleep Recommendations

About the Sleep Quality Estimator

Sleep quality is not just about how many hours you spend in bed — it's about sleep efficiency, sleep architecture, consistency, environment, and how you feel during the day. This estimator uses a validated framework drawn from the Pittsburgh Sleep Quality Index (PSQI) and current sleep science to assess your sleep across five key dimensions: duration, timing consistency, sleep environment, pre-sleep habits, and daytime function. The result is a comprehensive sleep score with targeted, actionable recommendations — not generic advice.

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Duration & Timing

How many hours you sleep and whether you go to bed and wake at consistent times. Consistency matters as much as total hours.

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Sleep Environment

Temperature, light, noise, and comfort. Your bedroom should be a sleep-optimised space — even small changes make measurable differences.

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Pre-Sleep Habits

Screen time, caffeine timing, exercise, alcohol, and your wind-down routine. What you do in the 2 hours before bed shapes the quality of sleep that follows.

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Daytime Function

How you feel during the day is the most honest measure of sleep quality. Fatigue, focus, mood, and energy are your sleep report card.

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Sleep Debt

Cumulative sleep deprivation compounds over days and weeks. The tool calculates your estimated weekly sleep debt and what it takes to recover.

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Targeted Fixes

Rather than generic sleep tips, recommendations are prioritised by which dimensions scored lowest — so you fix what's actually broken first.

The Sleep Stages — What Happens When You Sleep

Stage Type Duration / Cycle What Happens What Disrupts It
Stage 1 Light NREM 1–7 minutes Transition from waking to sleep. Muscles relax, heart rate slows. Easily woken. Noise, light, stimulants, anxiety
Stage 2 Light NREM 10–25 minutes Body temperature drops, heart rate slows further. Sleep spindles consolidate memory. Makes up ~50% of total sleep. Irregular schedule, alcohol late at night
Stage 3 Deep NREM 20–40 minutes (early cycles) Slow-wave sleep. Physical restoration — muscle repair, immune function, growth hormone release. Hardest to wake from. Alcohol, sleep deprivation debt, late eating, age
REM REM Sleep 10–60 min (increases each cycle) Emotional processing, memory consolidation, creativity. Dreams occur here. Brain highly active. Alcohol, cannabis, many medications, inconsistent schedule

How Much Sleep Do You Actually Need?

The National Sleep Foundation recommends 7–9 hours for adults (18–64) and 7–8 hours for older adults (65+). But individual variation is real — approximately 3% of people are genuine short sleepers who function well on 6 hours. The key question isn't "how many hours am I getting?" but "do I feel genuinely rested?"

  • Teenagers (14–17): 8–10 hours. Growth, learning, and emotional regulation all depend on it.
  • Young adults (18–25): 7–9 hours. This age group chronically undersleeps due to social schedules.
  • Adults (26–64): 7–9 hours. Quality matters increasingly as deep sleep naturally declines with age.
  • Older adults (65+): 7–8 hours. Earlier wake times are normal; total sleep need doesn't decrease much.
  • After illness or intense training: Add 1–2 hours. Recovery sleep is a genuine biological need, not laziness.

How to Improve Sleep Quality: The Evidence

Most sleep advice is generic. Here's what the research actually supports, in order of effect size:

  • Fix your wake time first. A consistent wake time — even on weekends — anchors your circadian rhythm faster than anything else. Going to bed at the same time matters less.
  • Get morning light within 30–60 minutes of waking. This resets your circadian clock, advances your melatonin onset, and improves sleep pressure at night.
  • Keep your bedroom below 19°C (66°F). Core body temperature must drop to initiate and maintain sleep. A cool room is one of the strongest environmental levers.
  • Cut caffeine after 1–2pm. Caffeine's half-life is 5–6 hours — a 3pm coffee is still 50% active at 8pm, directly reducing deep sleep.
  • Avoid alcohol within 3 hours of sleep. Alcohol fragments sleep architecture, suppresses REM, and causes early wake-ups as it metabolises.
  • Build a wind-down routine. A consistent 30–60 minute pre-sleep routine signals your nervous system to shift from sympathetic (alert) to parasympathetic (rest) mode.
Frequently Asked Questions
What is a good sleep quality score?
Scores of 75–100 indicate excellent sleep hygiene with minimal room for improvement. 55–74 is good with specific areas worth optimising. 35–54 suggests meaningful sleep quality issues that are affecting daytime function. Below 35 indicates significant chronic sleep problems that warrant attention — and possibly a conversation with a doctor or sleep specialist.
What is sleep debt and can you recover it?
Sleep debt is the cumulative shortfall between the sleep you need and the sleep you get. Research shows you can recover acute sleep debt (from a few days) with extra sleep, but chronic sleep deprivation has lasting effects on cognitive function and metabolic health. You cannot fully "bank" sleep in advance. The best strategy is consistent adequate sleep rather than cycles of deprivation and catch-up.
Why do I wake up tired even after 8 hours?
Waking tired after sufficient hours usually points to one of four causes: (1) poor sleep quality — you're in bed but not getting restorative deep sleep or REM; (2) sleep phase misalignment — you're sleeping at the wrong time for your chronotype; (3) sleep apnea or other sleep disorders causing micro-arousals you don't remember; (4) nutrient deficiencies (iron, vitamin D, B12) affecting energy production. This tool can identify the first two; a doctor should assess the latter two.
Does screen time really affect sleep?
Yes — but the mechanism is dual. Blue light from screens suppresses melatonin production (by up to 50% for 2 hours of evening exposure), and the psychological engagement of social media, news, and video keeps the nervous system in an alert state. Both effects delay sleep onset. The evidence for blue light glasses is weaker than marketed; avoiding stimulating content is more effective than filtering the light.
Is it better to sleep less but consistently, or more but irregularly?
Consistency is likely more important than most people realise. Research from Harvard found that irregular sleep schedules were associated with lower GPAs and worse health outcomes, independent of total sleep duration. "Social jetlag" — the mismatch between your biological clock and your social schedule — is associated with obesity, metabolic syndrome, and depression. Aim for consistent timing first, then optimise duration.
What temperature should my bedroom be for sleep?
The research consensus points to 16–19°C (60–66°F) as optimal for most adults. Core body temperature naturally drops by 1–2°C to initiate sleep, and a cool environment accelerates this. Temperatures above 24°C significantly fragment sleep and reduce slow-wave (deep) sleep. A cooling mattress pad or keeping a window slightly open are the most practical interventions.

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