Sleep Calculator: Find Your Perfect Bedtime | SleepSway

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Perfect your sleep by aligning with your natural sleep cycles.
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Calculations are based on 90-minute sleep cycles and an average of 15 minutes to fall asleep.

Why do I feel so tired after 8 hours?

It's not just about how much you sleep, but when you wake up.

Think of your sleep like a series of 90-minute train rides. Once you get on the train (fall asleep), you have to ride it all the way to the next station (end of a cycle) to get off smoothly.

If your alarm goes off in the middle of the ride, while you're in deep sleep, your brain is forced to jolt awake from its "repair mode." That's why you feel groggy, disoriented, and like you've been hit by a truck, even if you got enough hours.

💡 The Secret

SleepSway calculates the arrival times of your "sleep trains." We help you wake up precisely when the train is at the station: during your lightest sleep stage. So you wake up feeling like you're ready to go.

The Science of Your Sleep

Sleep isn't just one long blackout. It's a complex cycle of recovery. Your body moves through 5 distinct stages about every 90 minutes.

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Stage 1

NREM / Drifting Off

You're navigating the space between awake and asleep. Muscles relax, and you might experience a hypnic jerk (twitch). Lasts 5-10 minutes.

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Stage 2

Light Sleep

Body temperature drops, heart rate slows. You spend ~50% of your night here. This is the optimal stage to wake up.

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Stage 3 & 4

Deep Sleep

The "dead to the world" phase. Essential for physical repair and immune health. Waking up here causes severe grogginess (sleep inertia).

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Stage 5: REM

Dream State

Your brain becomes highly active, processing emotions and solidifying memories. Muscles are temporarily paralyzed to prevent acting out dreams. Waking up *after* this stage often leaves you feeling mentally sharp.

How Much Sleep Do You Actually Need?

One size doesn't fit all. Your sleep needs change as you grow. Here's what the science suggests for your age group:

Age Group Age Range Recommended Hours
Newborns 0–3 months 14–17 hours
Infants 4–11 months 12–15 hours
Toddlers 1–2 years 11–14 hours
Preschoolers 3–5 years 10–13 hours
School Age 6–13 years 9–11 hours
Teenagers 14–17 years 8–10 hours
Young Adults 18–25 years 7–9 hours
Adults 26–64 years 7–9 hours
Older Adults 65+ years 7–8 hours

Source: National Sleep Foundation

The Science of Sound

Silence isn't always golden. "Colored" noise can mask disruptive sounds and tune your brain for deeper sleep.

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White Noise

The Masker

Sounds like: Static, A whirring fan.

Contains all frequencies at equal intensity. It creates a "wall of sound" that blocks out sudden noises like traffic or barking dogs.

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Pink Noise

The Soother

Sounds like: Steady rain, Rustling leaves.

Balanced and deeper. It lowers brain waves to improve stable sleep and may boost memory consolidation.

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Brown Noise

The Rumbler

Sounds like: Distant thunder, A waterfall.

The deepest of them all. Stronger in low frequencies, making it excellent for calming anxiety and quieting a racing mind.

Common Questions

How long does it really take to fall asleep?
For most people, it takes about 15 minutes to drift off. We built this buffer right into SleepSway's calculations. If you usually hit the pillow and are out cold in 2 minutes (or toss and turn for 30), just adjust the result time slightly in your head.
Is 4.5 hours of sleep survival mode?
It's the absolute minimum. 4.5 hours is exactly 3 full cycles. It's infinitely better than getting 5 hours (which wakes you up mid-deep-sleep), but it's not sustainable. Think of it as an emergency power-save mode. For long-term health, aim for 5 to 6 cycles (7.5 - 9 hours).
Wait, does this actually work?
Yes, because it's biology, not magic. Your brain has a rhythm (circadian rhythm + ultradian cycles). Fighting that rhythm is why you need three coffees in the morning. Working with it makes waking up feel natural, like your body decided to wake up on its own.
What if I wake up before my alarm?
Get up! Seriously. If your body wakes you up 10 minutes before your alarm, it means a cycle just finished. If you go back to sleep for those "extra 10 minutes," you'll start a new cycle, the alarm will interrupt it, and you'll wake up feeling worse. Trust your body.
How long should a power nap be?
Aim for 20 minutes for a quick energy boost without grogginess. Alternatively, go for a full 90 minutes to complete a full sleep cycle. Avoid napping for 30–60 minutes to prevent waking up during deep sleep.
Can I catch up on missed sleep?
Partly, but consistency is better. "Sleep debt" is real, but binge-sleeping on weekends can throw off your biological clock (social jetlag). It's better to add 15-30 minutes of extra sleep each night rather than sleeping in all day Sunday.
What is the best temperature for sleeping?
Your body needs to cool down to initiate sleep. Science suggests keeping your bedroom between 60-67°F (15-19°C) is optimal for most people to fall asleep faster and stay asleep.
Does white noise actually help you sleep?
Yes. It works by "masking." Your brain is wired to listen for sudden changes in silence (a survival instinct). White noise creates a consistent audio backdrop, so sudden creaks or car horns don't trigger your wake response.
What's the difference between White, Pink, and Brown noise?
It comes down to frequency.
• White Noise: High pitch (Static). Good for blocking.
• Pink Noise: Balanced (Rain). Good for deep sleep.
• Brown Noise: Low pitch (Thunder). Good for calming anxiety.

Scientific References