Circadian Rhythm Calculators & Sleep Optimization Tools

Optimize when you sleep,
not just how long.

CircadianIQ uses chronotype science, sleep timing, recovery patterns, and circadian biology to help you align sleep with your natural rhythm.

EVIDENCE-BASED
RESEARCH-BACKED
NO WEARABLE REQUIRED
The Tool Library

Sleep calculators & circadian rhythm tools

Eighteen science-backed instruments to map every dimension of your sleep — from chronotype to caffeine kinetics, melatonin onset to social jet lag.

01 / Daily Sleep Timing
5 TOOLS · FOUNDATIONAL
Popular

Chronotype Calculator

Identify whether you're a Lion, Bear, Wolf, or Dolphin based on validated chronobiology questionnaires.

~3 MINSCIENCE-BACKED
Popular

Sleep Calculator

Find your optimal bedtime working backward from your wake target across full 90-minute sleep cycles.

~1 MINSCIENCE-BACKED

Wake-Up Time Calculator

Determine the wake time that ends a cycle in light sleep, minimizing morning grogginess.

~1 MINSCIENCE-BACKED

Sleep Cycle Calculator

Map four to six 90-minute architectural cycles across your night with REM and NREM phase estimates.

~2 MINSCIENCE-BACKED
Popular

Sleep Debt Calculator

Quantify accumulated sleep deficit and design a measured recovery plan over the coming weeks.

~2 MINSCIENCE-BACKED

Nap Duration Calculator

Choose between power naps, recovery naps, or full-cycle naps based on time of day and sleep need.

~1 MINSCIENCE-BACKED
02 / Sleep Recovery & Performance
4 TOOLS · INTERMEDIATE

Melatonin Timing Calculator

Calculate your dim-light melatonin onset (DLMO) window and the ideal supplementation timing.

~2 MINSCIENCE-BACKED

Caffeine Half-Life Calculator

Track caffeine metabolism with personalized half-life estimates based on genetics, age, and tolerance.

~2 MINSCIENCE-BACKED

Sleep Efficiency Calculator

Calculate the percentage of time in bed actually spent asleep — a key clinical marker of sleep quality.

~1 MINSCIENCE-BACKED

Sleep Inertia Calculator

Estimate the grogginess window after waking and learn evidence-based strategies to clear it faster.

~2 MINSCIENCE-BACKED
03 / Shift Work & Special Schedules
4 TOOLS · CLINICAL

Social Jet Lag Calculator

Measure the gap between your weekday and weekend sleep midpoints — a strong predictor of metabolic risk.

~2 MINSCIENCE-BACKED

Shift Work Sleep Optimizer

Build a circadian-aligned schedule for night, rotating, or split shifts that protects long-term health.

~5 MINSCIENCE-BACKED

Jet Lag Recovery Planner

Pre-shift your rhythm before flight and accelerate adaptation with timed light, meals, and melatonin.

~4 MINSCIENCE-BACKED

Light Therapy Scheduler

Time bright light exposure to advance, delay, or stabilize your circadian phase with clinical precision.

~3 MINSCIENCE-BACKED
04 / Advanced Circadian Science
4 TOOLS · ADVANCED

Circadian Rhythm Calculator

Generate a personalized 24-hour map of body temperature, melatonin, cortisol, and alertness peaks.

~4 MINSCIENCE-BACKED

DLMO Estimator

Estimate dim-light melatonin onset — the gold-standard circadian phase marker used in research labs.

~3 MINSCIENCE-BACKED

REM Sleep Estimator

Approximate nightly REM and deep sleep distribution based on bedtime, duration, and cycle architecture.

~2 MINSCIENCE-BACKED

Chrononutrition Timing Tool

Align meal timing with your circadian phase to optimize insulin sensitivity, energy, and sleep onset.

~3 MINSCIENCE-BACKED
The Four Chronotypes

Sleep schedules designed around your wiring.

Your circadian preference isn't a choice — it's genetic architecture. Identify which of the four research-defined chronotypes matches your biology.

The Lion
~15% OF POPULATION

Early-rising achievers. Lions hit peak cognitive performance before most people finish their first cup of coffee — but fade quickly after sunset.

Wake5:30–6:00 AM
Sleep9:30–10:00 PM
Peak8 AM – 12 PM
RecoveryRapid & Deep
The Bear
~55% OF POPULATION

The solar-aligned majority. Bears follow the sun, hit a strong mid-morning productivity peak, and ride a steady energy curve through the day.

Wake7:00–7:30 AM
Sleep11:00 PM
Peak10 AM – 2 PM
RecoveryConsistent
The Wolf
~15% OF POPULATION

Genetically wired for evening genius. Wolves struggle with mornings, hit creative peak after dark, and benefit most from delayed-phase schedules.

Wake8:30–9:00 AM
Sleep12:00–1:00 AM
Peak5 PM – 12 AM
RecoverySlow Onset
The Dolphin
~10% OF POPULATION

Light, fragmented sleep with hyper-vigilance. Dolphins benefit most from rhythm anchoring, environmental control, and structured wind-down rituals.

Wake6:30 AM
Sleep11:30 PM
Peak10 AM – 12 PM
RecoverySensitive
The Method

How CircadianIQ works

Three steps from biological baseline to a daily protocol that respects how your body actually keeps time.

01

Complete your sleep assessment

A 5-minute validated questionnaire covering sleep timing, chronotype tendencies, light exposure, and lifestyle factors.

02

CircadianIQ analyzes the inputs

Our model evaluates:

  • Chronotype classification
  • Sleep timing variance
  • Recovery & debt patterns
  • Daily light exposure
  • Circadian phase alignment
03

Receive personalized recommendations

You get a calibrated protocol:

  • Optimal bedtime & wake time
  • Caffeine cutoff window
  • Workout timing
  • Meal timing guidance
  • Recovery & light protocols
The Underlying Biology

Sleep is a system. We map it.

A live look at the rhythms governing your day — body temperature, sleep pressure, melatonin, alertness, and metabolism.

CIRCADIAN RHYTHM CURVE
Core Body Temperature · 24h
Your master clock encoded as a 24-hour temperature oscillation, peaking late afternoon and troughing pre-dawn.
PEAK · 4PM 06:00 12:00 06:00
PROCESS S
Sleep Pressure
Adenosine accumulation over waking hours.
06h 22h
SLEEP ARCHITECTURE
REM / NREM
Five cycles · 90 min each.
REM N3
PINEAL OUTPUT
Melatonin Release
Onset ~21:00 · Peak ~03:00 · DLMO marker.
DLMO
PHARMACOKINETICS
Caffeine Decay
Half-life ≈ 5 hours · CYP1A2 dependent.
½ LIFE
SUBJECTIVE ALERTNESS
Two-Process Model — Alertness Across the Day
Alertness emerges from the interaction of homeostatic sleep pressure (Process S) and circadian wake drive (Process C).
DIP · 14:00 PEAK · 10:00 PEAK · 17:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00
2
DAILY ALERTNESS PEAKS
SEPARATED BY POST-LUNCH DIP
The Knowledge Library

In-depth sleep science guides

Seven curated knowledge clusters covering everything from circadian biology to chrononutrition — written by sleep researchers, reviewed by clinicians.

Standards & Methodology

Built on sleep science, not wellness vibes.

CircadianIQ is grounded in peer-reviewed chronobiology, transparent methodology, and clinical reasoning — not optimization theater.

PILLAR 01

Research-backed methodology

Every calculator references the underlying studies, validated questionnaires, and physiological models it derives from. Citations are linked, not implied.

PILLAR 02

Evidence-first recommendations

We distinguish between strong, moderate, and emerging evidence — and we never present preliminary findings as established consensus. Confidence is graded.

PILLAR 03

Practical, non-prescriptive guidance

CircadianIQ is an educational tool, not a medical service. We optimize for clarity and informed self-experimentation — never diagnosis or treatment.

RESEARCH FOUNDATIONS & INSTITUTIONAL REFERENCES
Coming Soon · CircadianIQ Pro

Your circadian intelligence dashboard

An always-on view of your rhythm — recovery, consistency, energy forecast, and tomorrow's optimal timing.

app.circadianiq.com / dashboard
CIRCADIAN SCORE
87 / 100
↑ +4 this week
RECOVERY SCORE
72 / 100
↓ -2 from yesterday
SLEEP CONSISTENCY
94 %
↑ 14-day streak
ENERGY FORECAST · NEXT 24H
NOW 12P 6P 12A 6A 12P
PEAK PRODUCTIVITY · TODAY
10:42 AM
— 11:14 AM  ·  +94 MIN
SECONDARY PEAK
4:18 PM
RECOMMENDED BEDTIME · TONIGHT
10:48 PM
± 12 min window · wake at 6:18 AM · 5 full cycles
CAFFEINE CUTOFF
2:00 PM
DIM LIGHT
9:30 PM
WORKOUT
5:45 PM
RECOVERY TRENDS · 7 DAYS
M T W T F S S
Frequently Asked

Sleep science, demystified.

The questions we hear most often — answered with evidence and without hedging.

View full knowledge base
Your circadian rhythm is a roughly 24-hour internal cycle that governs sleep-wake timing, hormone release, body temperature, alertness, and metabolism. It's regulated by the suprachiasmatic nucleus (SCN) in the hypothalamus, synchronized primarily by light exposure to specialized retinal cells called ipRGCs.
Chronotype is most reliably assessed using validated questionnaires like the Morningness-Eveningness Questionnaire (MEQ) or the Munich ChronoType Questionnaire (MCTQ). Both measure your natural sleep midpoint on free days — the most stable behavioral marker of your circadian phase. CircadianIQ's chronotype calculator is based on these instruments.
Yes — but slowly. The circadian system shifts by approximately 1 hour per day in either direction in response to coordinated zeitgebers: bright light exposure (especially morning light for phase advance), meal timing, exercise timing, and exogenous melatonin. Genetic chronotype (early vs. late) is far less malleable than daily phase position.
Social jet lag is the chronic misalignment between your biological sleep timing and your socially-imposed schedule, measured as the difference between your sleep midpoint on workdays vs. free days. A 2+ hour gap is associated with elevated risk for metabolic syndrome, mood disorders, and cardiovascular disease.
Caffeine's average half-life is approximately 5 hours, but individual variation is dramatic — driven largely by CYP1A2 genotype. For most people, caffeine consumed after 2:00 PM measurably reduces slow-wave sleep, even when subjective sleep quality feels unaffected. The conservative cutoff is 8–10 hours before intended bedtime.
Sleep inertia — the heavy grogginess on waking — is most pronounced when you're roused from deep NREM sleep. It can last 15 to 60+ minutes and reflects a transient state of reduced cerebral blood flow and prefrontal cortex activation. Strategies that shorten it: bright light, cold water, light physical activity, and waking from lighter sleep stages.
Light — especially short-wavelength blue light around 480 nm — suppresses pineal melatonin production through the ipRGC-SCN pathway. Even moderate evening light exposure (around 10 lux) can delay melatonin onset by 30+ minutes. Conversely, morning light is the strongest zeitgeber for advancing your circadian phase.
There isn't a universal ideal — there's a personal one. The optimal schedule aligns your sleep window with your biological chronotype, maintains consistent timing within ±30 minutes across all 7 days of the week, and delivers 7–9 hours of total sleep opportunity. Consistency matters more than any specific clock time.
Stop optimizing blindly

Stop optimizing sleep blindly.

Use circadian science to discover your ideal sleep schedule, recovery timing, and peak performance windows.