How sleep cycles work
Sleep is not one flat state. Most people move through lighter sleep, deeper sleep, and REM sleep several times a night. A complete round is commonly approximated as 90 minutes. The calculator uses that practical average, then adds a fall-asleep buffer because most people do not fall asleep the moment they lie down.
Waking near the end of a cycle often feels easier than waking from deep sleep. This is why two bedtimes only 30 minutes apart can feel very different the next morning. The result is guidance, not a medical diagnosis.
Fajr-aware sleep planning
Fajr-aware mode fetches today's Fajr time for major Pakistani cities using the Aladhan prayer-times API. It then shows three practical patterns: sleeping early and staying awake, sleeping before Fajr and returning for one more cycle, or using a split-sleep pattern. This is a planning aid, not a religious ruling.
Sleep hygiene basics
A calculator helps with timing, but consistent habits matter more. Keep your bedtime and wake time steady, reduce bright screens before bed, avoid heavy meals late at night, and keep the room cool and dark. If poor sleep is persistent, especially with snoring or breathing pauses, get clinical advice.
FAQ
What time should I go to bed to wake up at 6 AM?
For 5 full cycles, sleep by 10:15 PM if you use the default 15-minute fall-asleep buffer. For 6 cycles, sleep by 8:45 PM.
Is the 90-minute sleep cycle real?
Yes. Adults move through light, deep, and REM sleep in cycles that average around 90 minutes, although the exact length varies by person and night.
How many hours of sleep do I need?
Most adults need 7 to 9 hours. Teens generally need 8 to 10 hours, while many adults over 65 do well with 7 to 8 hours.
Why do I wake up groggy?
One common reason is waking during deeper sleep. Shifting bedtime or wake time by 15 to 30 minutes can help you wake closer to the end of a cycle.
How do I wake up easily for Fajr?
Sleep earlier and aim for 5 or 6 complete cycles before Fajr. A consistent bedtime, less screen time before bed, and preparing your alarm before sleeping also help.
Should I sleep after Fajr prayer?
If you have not slept enough, a short planned sleep block can help. Keep it intentional so it does not push your next night's bedtime too late.
Is 6 hours of sleep enough?
For most adults, 6 hours is below the usual recommendation. Occasional short sleep happens, but chronic short sleep can affect health and alertness.
What is Qailula?
Qailula is a short midday nap. A 20 to 30 minute nap before late afternoon can improve alertness without making night sleep harder for many people.
Does this work with local time zones?
Yes. The calculator uses the time on your device and handles crossing midnight, such as sleeping before midnight and waking after midnight.
Why does the calculator show four times?
Different people need different sleep amounts. The calculator shows several cycle-aligned options and highlights 5 cycles as a common adult target.