The science of sleep and the pre-dawn alarm

Waking for Fajr feels brutal some days and effortless others — often at the same clock time. The difference is usually where in a sleep cycle the alarm lands.

Cycles, not hours

Sleep runs in roughly 90-minute cycles, from light sleep into deep sleep and back through REM. An alarm that lands mid-deep-sleep produces that drugged, headachy wake-up. The same alarm thirty minutes later, at the end of a cycle, can feel almost gentle.

Count back in whole cycles

From your Fajr time, count back five cycles (7.5 hours) or four (6 hours) and aim your bedtime there. 6 hours of well-aligned sleep often beats 7 badly-aligned ones.

The 20-minute rule

Screens off twenty minutes before the target. Not for digital-detox reasons — simply because "one more scroll" is how a 9:40 bedtime becomes 11:15, and the arithmetic dies.