Get Your Personalized Sleep Schedule in 60 Seconds

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Step 1: What do you know?

Step 2: When do you need to wake up?

Step 3: How many hours of sleep do you need?

8 hours

Most adults need 7-9 hours. Adjust based on how you feel.

Step 4 (Optional): Personalized Sleep Assessment

Why take this assessment? This 3-minute quiz analyzes your chronotype (morning lark vs. night owl) and caffeine tolerance to personalize your schedule. Your chronotype is genetically influenced and affects optimal sleep timing by 30-90 minutes. Caffeine metabolism varies 40x between individuals—we'll help you find your ideal cutoff time.

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Your optimal bedtime is

10:30 PM

To wake at 6:00 AM feeling refreshed

Your Sleep Cycle Breakdown

7.5 hours Total Sleep

5 cycles Complete 90-min Cycles

Why 90-minute cycles? Your sleep alternates between light (N1, N2), deep (N3), and REM sleep in roughly 90-minute cycles (range: 80-120 min). Waking at the end of a complete cycle minimizes sleep inertia—that groggy feeling when waking mid-cycle.

NIH: Brain Basics - Understanding Sleep • Carskadon & Dement (2005)

Your Daily Circadian Optimization Plan

Follow these four key actions to support your natural rhythm:

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Morning Light Exposure

Get bright light between 6:00-7:00 AM

Anchors your circadian clock and boosts alertness. Get 2-10 minutes of outdoor light within 1 hour of waking. If outdoors isn't possible, use bright indoor lights for 10-30 minutes—but know that outdoor light is 50x brighter (10,000+ lux outdoors vs ~500 lux indoors). Morning light advances your phase response curve, helping you wake earlier naturally.

Pro tip: Even on cloudy days, outdoor light delivers vastly more photons to your retina than any indoor lighting. On sunny days, you may only need 2-5 minutes; on overcast days, aim for 10 minutes.

⏰ Pre-waking light strategy: If you struggle with early mornings, use a timer-based light (smart bulb or sunrise alarm clock) set to turn on 45-60 minutes before your wake time. Light works through closed eyelids to activate your circadian system before you even wake up. Research shows this can increase total sleep time and make waking easier.

Khalsa et al. (2003) • Wright et al. (2013) • Zeitzer et al. (2000) - Pre-waking light

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Sunset Light Exposure

View sunset light (estimate based on your location)

Viewing low-angle sunlight within 1 hour of sunset protects your retina against the harmful effects of bright light exposure later at night. This "light adaptation" primes your melanopsin-containing retinal ganglion cells to be less sensitive to artificial light between 11 PM and 4 AM—the most critical window for avoiding dopamine suppression and mood disruption.

Why this matters: Research shows that light exposure between 11 PM-4 AM can suppress dopamine release in the habenula (part of your brain's reward circuitry), negatively affecting mood and motivation. Sunset viewing provides a biological buffer against this effect.

Fernandez et al. (2018) - Melanopsin cells • Huberman Lab: Master Your Sleep

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Caffeine Cutoff

Last caffeine by 2:00 PM

Caffeine blocks adenosine receptors, preventing sleep pressure buildup. With a 5-6 hour half-life, a conservative 8-hour cutoff before bed prevents sleep onset delay and reduced deep sleep.

Understanding Adenosine Sleep Pressure:

Adenosine builds up in your brain throughout the day, creating "sleep pressure" that makes you feel tired:

Wake

Bedtime

☕ What caffeine does: It blocks adenosine from binding to receptors, temporarily masking tiredness. But adenosine keeps building up behind the scenes. When caffeine wears off, all that accumulated sleep pressure hits at once (the "caffeine crash"). Late caffeine = sleep pressure still masked at bedtime.

Drake et al. (2013) • Clark & Landolt (2017) • Huberman Lab: Adenosine & Sleep Pressure

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Wind-Down Routine & Evening Light Positioning

Begin winding down at 9:30 PM

Dim lights (below 50 lux), reduce blue light exposure (450-480 nm wavelength), and start relaxing activities to trigger melatonin release. Bright light in the evening delays your circadian clock.

Critical light positioning tip: In the evening, use low-positioned lights (floor lamps, table lamps) rather than overhead lights. Here's why: Your retina has neurons that detect light coming from above (which signals daytime) versus light from below or eye-level. Overhead lights activate the "daytime" neurons more strongly, suppressing melatonin and keeping you alert. Low/floor lamps minimize this activation while still providing functional lighting.

⚠️ Critical window (11 PM - 4 AM): Avoid bright light entirely during this window if possible. Even brief exposure can suppress dopamine and disrupt mood-regulating brain circuits (habenula activation). If you must use light, keep it as dim as possible and positioned low.

🧘 NSDR (Non-Sleep Deep Rest) Protocols for Sleep Preparation

NSDR protocols activate the parasympathetic nervous system, reduce cortisol, and help transition your brain into a sleep-ready state. These evidence-based practices (recommended by Prof. Andrew Huberman) can significantly improve sleep onset and quality when done 30-60 minutes before bed:

NSDR Protocol (Virtusan App) - Guided protocol designed for sleep preparation
10-Minute NSDR - Short session for busy evenings
20-Minute NSDR - Full session for optimal relaxation
Yoga Nidra for Sleep (30 min) - Deep body scan meditation
Insight Timer (Free App) - Thousands of guided sleep meditations

How it works: NSDR mimics early sleep stages by slowing brain waves, reducing sympathetic nervous system activity, and increasing GABA (the calming neurotransmitter). Regular practice can also help you fall back asleep if you wake during the night.

🌡️ Temperature Optimization

Your core body temperature naturally drops 1-2°F to initiate sleep—this is controlled by your circadian rhythm. Support this process:

Optimal bedroom temperature: 60-67°F (15-19°C) - Cooler than most people think. Your body needs to dissipate heat to trigger sleep.
Body temperature curve: Core temp peaks in late afternoon (4-6 PM), then drops throughout evening. Lowest point is ~2-4 AM, then rises before waking.
Exercise timing: Vigorous exercise raises core temp by 2-3°F. Schedule workouts at least 4-6 hours before bed to allow temperature to drop. Morning or early afternoon exercise is ideal.
Hot bath/shower hack: Taking a hot bath 60-90 minutes before bed paradoxically helps sleep. When you exit, blood vessels dilate to release heat, dropping core temperature faster.
Keep extremities warm: Wear socks or use a hot water bottle for feet. Warm hands/feet increase blood flow to periphery, pulling heat away from core.

Why this matters: A 2-3°F drop in core body temperature is one of the strongest biological signals for sleep onset. Fighting this (too-warm room, late exercise) delays melatonin release and sleep onset by 30-60 minutes.

Chang et al. (2015) • Wood et al. (2013) • Haghayegh et al. (2019) - Temperature & Sleep • Huberman Lab: Temperature & Sleep

Optimal Nap Windows

Strategic napping can boost alertness and performance without disrupting nighttime sleep. Here are your personalized nap windows:

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Power Nap Window (20 minutes)

Best between 1:00-2:00 PM

Short naps (15-20 minutes) provide quick refreshment without entering deep sleep. You'll wake feeling alert within 5 minutes. Ideal for busy schedules or when you need a quick energy boost without grogginess.

How to power nap: Set an alarm for 20 minutes. Find a quiet, dark space. You don't need to fully fall asleep—even resting with eyes closed provides benefits. Avoid napping past 3 PM if you sleep before midnight.

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Recovery Nap Window (60-90 minutes)

Best between 1:00-2:30 PM (start time)

Longer naps (60-90 minutes) complete a full sleep cycle, including REM sleep, which aids memory consolidation and creativity. A 90-minute nap avoids waking during deep sleep (sleep inertia). Only use when significantly sleep-deprived or for cognitive performance.

⚠️ Important timing: Complete your nap at least 6 hours before bedtime. Late naps reduce sleep pressure (adenosine buildup) and can delay sleep onset by 1-2 hours. If you're not sleep-deprived, stick to 20-minute power naps.

Milner & Cote (2009) - Nap Duration & Sleep Inertia • Huberman Lab: Napping Science

Circadian-Aligned Meal Timing

When you eat affects your circadian rhythm, metabolism, and sleep quality. These windows align with your body's natural digestive cycles:

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First Meal Window (Breaking the Fast)

Eat between 7:00-9:00 AM

Your first meal acts as a secondary zeitgeber (time cue) that helps synchronize your circadian rhythm. Eating within 1-3 hours of waking optimizes metabolic hormones (insulin sensitivity peaks in morning) and aligns your peripheral clocks (liver, muscles) with your central clock (brain).

Metabolic benefits: Morning eating is associated with better glucose control, higher thermogenesis (calorie burning), and improved cognitive performance. Delaying first meal beyond 4 hours post-wake can desynchronize your circadian rhythm.

Poggiogalle et al. (2018) - Circadian Rhythms & Meal Timing • Garaulet & Gómez-Abellán (2014)

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Last Meal Window (Dinner Cutoff)

Finish eating by 7:30 PM

Eating within 2-3 hours of bedtime disrupts sleep architecture by raising core body temperature, increasing insulin, and activating digestion when your body expects rest. Late meals are also linked to reduced REM sleep, increased sleep fragmentation, and weight gain due to lower evening metabolic rate.

The 12-hour eating window: Ideally, compress all eating into a 12-hour window (e.g., 7 AM-7 PM). This time-restricted feeding pattern strengthens circadian rhythms, improves insulin sensitivity, and enhances sleep quality. Longer fasting periods (14-16 hours overnight) show additional metabolic benefits.

⚠️ What about hunger before bed? If genuinely hungry (not just habitual), choose a small, low-glycemic snack (e.g., handful of nuts, Greek yogurt). Avoid large meals, high-sugar foods, or spicy foods within 3 hours of sleep.

St-Onge et al. (2016) - Meal Timing & Sleep • Longo & Panda (2016) - Time-Restricted Feeding

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The Science of Sleep Optimization

Understanding how sleep works helps you optimize it. Here's the research behind our recommendations.

90-Minute Sleep Cycles Explained

Sleep architecture follows predictable ultradian rhythms. A complete cycle takes approximately 90 minutes (range: 80-120 min) and progresses through:

Light Sleep (N1, N2): Transition phase, easy to wake from
Deep Sleep (N3): Slow-wave sleep, physical restoration, memory consolidation
REM Sleep: Rapid eye movement, dreaming, emotional processing, learning

Deep sleep predominates in early cycles (first 3-4 hours); REM sleep increases toward morning. Waking during deep sleep causes grogginess (sleep inertia); waking at cycle completion feels natural.

Why this matters: Timing sleep in 90-minute increments (6, 7.5, or 9 hours) maximizes complete cycles and minimizes mid-cycle waking.

Sources: NIH Brain Basics: Understanding Sleep • Carskadon & Dement (2005) • Ferrara & De Gennaro (2011)

Understanding Your Chronotype

Chronotype describes your genetically-influenced sleep-wake preference:

Morning Larks (20-25%): Wake naturally before 7 AM, peak alertness morning/midday
Night Owls (20-25%): Wake naturally after 9 AM, peak alertness evening/night
Intermediate (50-60%): Flexible sleep timing, moderate preferences

Chronotype is partly determined by PER3, CLOCK, and other gene variants. It changes across lifespan: children are intermediate, teenagers shift late (delayed phase), adults gradually shift earlier with age.

Why this matters: Fighting your chronotype causes chronic sleep deprivation. Our quiz (based on the validated Morningness-Eveningness Questionnaire) adjusts recommendations by 30-90 minutes to match your biology.

Sources: Horne & Östberg (1976) - Original MEQ Study • Jones et al. (2019) - Genome-wide Study

Circadian Rhythm & Light Exposure

Your circadian rhythm is a ~24-hour biological clock regulated by the suprachiasmatic nucleus (SCN) in the hypothalamus. Light is the primary zeitgeber (time cue) that synchronizes your internal clock to the external day-night cycle.

The Phase Response Curve:

Morning light (2-3 hrs after waking): Advances your clock → wake earlier naturally
Afternoon light: Minimal effect on phase
Evening light (2 hrs before bed): Delays your clock → stay up later

Optimal intensity: 2,000-10,000 lux (outdoors on overcast day = ~10,000 lux; bright indoor = ~500 lux). Even 10-15 minutes of morning light has measurable effects.

Sources: Khalsa et al. (2003) - Phase Response Curve • Wright et al. (2013) • Huberman Lab: Master Your Sleep

Phase Shifts: How to Deliberately Adjust Your Schedule

Want to become a morning person? Need to adjust for a new work schedule? Understanding phase shifts lets you intentionally move your circadian clock.

🌅 Phase Advance (Wake Earlier)

Goal: Shift your schedule earlier (e.g., night owl → early bird)

Light timing: Get bright light immediately upon waking (even if it's still dark—use bright indoor lights)
Evening discipline: Avoid bright light 2-3 hours before current bedtime
Incremental shifts: Move wake time earlier by 15-30 minutes every 2-3 days
Timeline: Expect 1-2 weeks to shift 60-90 minutes earlier

Example: Currently wake at 8 AM, want to wake at 6:30 AM. Week 1: wake at 7:30 AM + immediate bright light. Week 2: wake at 7:00 AM. Week 3: wake at 6:30 AM. Maintain strict light discipline throughout.

🌙 Phase Delay (Wake Later)

Goal: Shift your schedule later (e.g., for night shift or travel west)

Light timing: Get bright light in the evening (2-3 hours before current bedtime)
Morning avoidance: Avoid bright light for first 2-3 hours after waking (wear sunglasses if necessary)
Incremental shifts: Move bedtime later by 30-60 minutes every 2-3 days
Timeline: Easier than phase advances; 3-5 days per hour of shift

Example: Currently sleep 10 PM-6 AM, need to shift to midnight-8 AM for new job. Days 1-3: sleep 10:30 PM-6:30 AM, bright light 7-9 PM. Days 4-6: sleep 11 PM-7 AM, bright light 8-10 PM. Days 7-9: sleep 11:30 PM-7:30 AM. Final: midnight-8 AM.

⚠️ Important Warnings

Don't rush: Shifting too fast (>60 min/day) often fails and disrupts sleep quality
Consistency matters: Weekend deviations reset progress—stick to new schedule 7 days/week
Sleep debt caution: Don't attempt phase shifts while sleep deprived—catch up first
Meal timing helps: Eating at your new target times reinforces the shift

Why this works: The SCN responds to light exposure timing with predictable phase responses. Morning light increases cortisol and suppresses evening melatonin release (advance). Evening light delays melatonin onset and pushes circadian phase later (delay). These effects compound over days when applied consistently.

Sources: Khalsa et al. (2003) - Phase Response Curve • Burgess et al. (2017) - Circadian Phase Shifting • Huberman Lab: Phase Shifts

Caffeine Timing Strategy

Caffeine is an adenosine receptor antagonist. Adenosine builds up during waking hours, creating sleep pressure. Caffeine blocks this signal, preventing you from feeling tired.

Key pharmacology:

Half-life: 5-6 hours (varies by genetics, age, medications)
Quarter-life: 10-12 hours (25% still active)
Sleep impact: Delays sleep onset, reduces deep sleep even at low doses

Why 8-hour cutoff: Conservative buffer accounts for individual variation. If you sleep at 10:30 PM, last caffeine by 2:30 PM ensures minimal sleep disruption.

Sources: Drake et al. (2013) • Clark & Landolt (2017) • Huberman Lab: Master Your Sleep

Blue Light & Melatonin

Melatonin (the "sleep hormone") is secreted by the pineal gland in response to darkness. Blue light (450-480 nm wavelength) is particularly effective at suppressing melatonin.

Evening light exposure effects:

Bright light (>100 lux): Delays melatonin onset by 30-60 min
Blue light from screens: Most potent suppressor per lux
Red/amber light: Minimal melatonin suppression

Practical application: Dim lights below 50 lux starting 1-2 hours before bed. Use blue-light filters or amber glasses if screens are necessary.

Sources: Chang et al. (2015) • Wood et al. (2013) • Huberman Lab: Master Your Sleep

Sleep Inertia: Why You Feel Groggy

Sleep inertia is that grogginess upon waking, lasting 5-30 minutes (sometimes longer). It's caused by waking during deep slow-wave sleep when:

Brain activity is at its lowest
Transition to wakefulness is incomplete
Cognitive performance is temporarily impaired

The solution: Wake at the end of a complete 90-minute cycle when you're naturally in lighter sleep or REM. This is why sleeping 7.5 hours often feels better than 8 hours—you're waking at cycle completion, not mid-cycle.

Sources: Ferrara & De Gennaro (2011) • Sleep Foundation

Frequently Asked Questions

For most adults needing 7.5 hours of sleep, the optimal bedtime to wake at 6:00 AM is 10:30 PM. This allows for 5 complete 90-minute sleep cycles. If you need 9 hours, go to bed at 9:00 PM (6 cycles). Use the calculator above for personalized recommendations.

Most adults need 5-6 complete sleep cycles per night (7.5-9 hours). Age, activity level, and individual variation affect this. If you consistently feel refreshed with 4 cycles (6 hours), that may be sufficient for you. Track how you feel and adjust accordingly.

Take our chronotype quiz above to find out. Morning people (early chronotypes) naturally wake before 7 AM and feel alert immediately. Night owls (late chronotypes) prefer waking after 9 AM and peak in the evening. Most people fall somewhere in between. Your chronotype is partly genetic and changes with age.

Grogginess upon waking (sleep inertia) usually means you woke during deep sleep rather than at the end of a cycle. It can also result from insufficient total sleep, inconsistent sleep timing, or sleep disorders. Try adjusting your bedtime in 90-minute increments and maintaining a consistent schedule for 7-14 days.

No. This calculator provides general guidance based on circadian science and sleep architecture research. It is not medical advice and does not diagnose or treat sleep disorders. If you suspect a condition like insomnia or sleep apnea, consult a healthcare provider. Individual sleep needs vary.

Important Disclaimer

Not Medical Advice: This tool provides general guidance based on circadian science. Results are not medical advice and are not a substitute for professional healthcare. Individual sleep needs vary.

Assumptions: We assume a 90-minute average sleep cycle (yours may vary by ±20 minutes). Chronotype assessment is based on a shortened questionnaire; full clinical assessment is more precise.

If You Have Concerns: If you suspect a sleep disorder (chronic insomnia, sleep apnea), consult a healthcare provider. These recommendations assume generally healthy adults without sleep disorders.

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