NightOwl Sleep Calc is a free sleep calculator that helps you plan bedtimes and wake-up times using sleep cycles, sleep latency (how long it takes you to fall asleep), and a wake window (a small flexible range instead of one exact minute). If you’ve ever woken up groggy even after “enough” hours of sleep, timing your wake-up closer to the end of a cycle can help.
This isn’t a medical tool—just practical sleep math. Pick a wake-up time to get recommended bedtimes, or choose “Bedtime now” to see the best wake-up windows based on your settings. Adjust the sliders to match your real-life routine, and use the wake window to give yourself a little breathing room.
How to use this sleep calculator
Choose a mode: “Wake up at…” for bedtime suggestions, or “Bedtime now” for wake-up suggestions.
Set your Tomorrow Goal: Pick a goal (Sharp, Survive, or Recover) to get a tailored cycle recommendation and nap timing.
Set your sleep latency: how long you usually take to fall asleep (many people are around 10–20 minutes).
Set cycle length: 90 minutes is typical, but you can adjust if you tend to run shorter or longer.
Pick a wake window: a small range (like 10–15 minutes) so you can aim for a window, not a single exact time.
Pick an option: choose the cycle count that fits your schedule, then copy or share the plan.
These common scenarios show how a sleep calculator can help you plan around real life. Your results may differ based on settings, but the idea is the same: plan sleep in full cycles and account for the time it takes to fall asleep.
If you need to wake up early
Select your wake-up time in “Wake up at…” mode. Most people feel best with about 5–6 cycles, but if you’re short on time, 4 cycles can be a workable minimum.
If you’re going to bed now
Tap “Bedtime now” to use the current time. Picking a wake time near the end of a cycle can reduce sleep inertia—that heavy, foggy feeling.
If you only have limited time
Choose a lower cycle count. Even if you can’t get a full night, waking closer to a cycle boundary may feel better than waking from deep sleep.
If you’re always "in bed" longer
Increase sleep latency to match your routine. This makes recommendations more realistic if you tend to lie awake or wind down for a while.
What is a sleep cycle?
Sleep isn’t one steady state—your brain moves through repeating stages, including lighter sleep, deeper sleep, and REM. A full sleep cycle often averages around 90 minutes, though it varies by person and by night.
What is sleep latency?
Sleep latency is the time it takes to fall asleep after you get into bed. Many people are around 10–20 minutes, but stress, caffeine, late screens, or irregular schedules can increase it.
What is a wake window?
A wake window is a small flexible range around a recommended time (for example, 10–15 minutes). It adds flexibility while staying close to an end-of-cycle wake-up.
How many sleep cycles do I need?
Many adults feel best with about 5–6 full cycles, which is roughly 7.5–9 hours of sleep time. 4 cycles can be a workable minimum when short on time.
Why 90-minute cycles?
It's a typical average, but if your results consistently feel early or late, try adjusting cycle length by a few minutes in settings.
What is sleep inertia?
The groggy, heavy feeling after waking—especially from deep sleep. Timing your alarm closer to a cycle boundary can make waking feel smoother.
Can this replace medical advice?
No. This tool is educational. If you have persistent insomnia or severe daytime sleepiness, consider talking with a clinician.
🎭 What is Meme Mode?
Meme Mode swaps out practical sleep advice for playful roasts and humor based on your sleep schedule. It's a fun way to see your sleep habits in a new light—whether you're a "chaotic night owl" or an "overachiever early bird." Toggle it on in Settings to add some personality to your results.
🎫 What is a Sleep Ticket?
A Sleep Ticket is a shareable graphic showing your sleep personality, bedtime, and wake time—perfect for Instagram Stories. After calculating your sleep times, pick one of the three results, then tap "Share Sleep Ticket" to generate a personalized card with your sleep type (like Night Owl, Early Bird, or Cycle Optimizer), a fun quote, and optional challenge stickers to engage your friends.
🎯 What are Challenge stickers?
Challenge stickers are interactive prompts you can add to your Sleep Ticket—things like "Post yours 👇" or "Roast my schedule." They're designed to spark engagement when you share your ticket on social media. Tap the Challenge button in the Sleep Ticket modal to cycle through different options.
Need a quick reset? Pick a nap type to get a recommended wake window based on the current time.
Select a nap to see your wake window.
Quick Nap Guide
Coffee Nap (15m)
Drink coffee, then nap immediately. Wake up right as the caffeine kicks in.
Power Nap (20m)
Boosts alertness and motor performance without entering deep sleep (no grogginess).
Full Cycle (90m)
Includes all sleep stages (including REM). Best for creativity and emotional reset, but takes longer to wake up from.
Napping is an art form
Learn why some naps leave you groggy and how to use coffee naps for maximum energy.
