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Accurate Sleep Calculator

Find your ideal bedtime or wake-up time based on scientific 90-minute sleep cycles. Better sleep starts here.

Calculate Sleep Time

3 cycles 4 cycles 5 cycles 6 cycles

Your Age Group

When Should You Sleep?

Choose your preferred wake-up or bedtime, adjust the number of sleep cycles, and hit Calculate to find your perfect sleep schedule.

Understanding Sleep Stages

Light Sleep (N1)

5–10 min

Transition phase. Easy to wake. Your body begins to relax.

Light Sleep (N2)

10–25 min

Heart rate slows. Body temperature drops. You're disengaged from surroundings.

Deep Sleep (N3)

20–40 min

Most restorative phase. Body repairs muscles, builds bone, boosts immunity.

REM Sleep

10–60 min

Dream stage. Brain processes emotions, consolidates memories. Eyes move rapidly.

Did you know? Each sleep cycle lasts about 90 minutes. Waking up at the end of a cycle (during light sleep) makes you feel refreshed, while waking mid-cycle causes grogginess — known as sleep inertia.

Recommended Sleep by Age Source: National Sleep Foundation & CDC

👶
Newborn (0–3 months)
14–17 hrs
🍼
Infant (4–11 months)
12–15 hrs
🧒
Toddler (1–2 years)
11–14 hrs
🎨
Preschool (3–5 years)
10–13 hrs
📚
School-age (6–13 years)
9–11 hrs
🎓
Teenager (14–17 years)
8–10 hrs
🧑‍💻
Young Adult (18–25 years)
7–9 hrs
💼
Adult (26–64 years)
7–9 hrs
🌅
Older Adult (65+ years)
7–8 hrs

Frequently Asked Questions

A complete sleep cycle lasts approximately 90 minutes and includes light sleep, deep sleep, and REM sleep. Waking up at the end of a cycle — when you're in light sleep — makes you feel refreshed and alert. Waking mid-cycle causes grogginess (sleep inertia). Our calculator uses this 90-minute rhythm to find your optimal times.
According to the National Sleep Foundation and the CDC, adults aged 18–64 need 7–9 hours of sleep per night. Older adults (65+) need 7–8 hours. However, individual needs vary — some people feel great on 7 hours, while others need 9. The best gauge is how you feel during the day.
Sleep inertia is that groggy, disoriented feeling when you wake up mid-cycle (during deep sleep). It can last 15–60 minutes and impair alertness. The best way to avoid it is to wake up at the end of a sleep cycle — which is exactly what this calculator helps you do. Exposure to bright light immediately after waking also helps clear sleep inertia faster.
While extra sleep on weekends can help you feel less tired temporarily, research from the University of Colorado Boulder found that "social jet lag" from irregular sleep patterns increases the risk of metabolic and cardiovascular problems. It's far better to maintain a consistent sleep schedule every night than to try to "make up" sleep on weekends.
The 10-3-2-1-0 rule is a popular sleep hygiene framework backed by sleep science: 10 hours before bed — no more caffeine. 3 hours before — no more food or alcohol. 2 hours before — no more work. 1 hour before — no more screens. 0 — the number of times you hit snooze. While individual results vary, each rule is supported by sleep research.