Short answer
It depends on how you sleep. In the Hanafi school, sleep breaks wudu when you lie down, sleep on your side, or lean so heavily that you would fall if the support were taken away. Dozing while sitting firmly on your seat, standing, or in the postures of prayer does not break it. The other schools differ on the details.
Sleep is not itself a breaker. It breaks wudu when the body is so relaxed that wind could pass unnoticed: lying down, on one side, or reclining against something so that removing it would make you fall. Sleep while sitting with the seat firmly on the ground, standing, or in ruku and sajdah does not break wudu.
Other madhhabs
- Shafi'i
- Any sleep breaks wudu unless you sleep sitting with your seat firmly on the ground.
- Maliki
- Deep sleep breaks wudu in any posture. Light sleep, in which you would notice something happening, does not.
- Hanbali
- All sleep breaks wudu except a little sleep while sitting or standing.
Explanation
Scholars treat sleep as a sign, not a breaker in itself. While you sleep, your body relaxes and you cannot tell if wind passed. So the question is whether your posture makes that likely. A hadith calls the eyes the "drawstring" of the back passage: when they close in sleep, the drawstring loosens.
In the Hanafi school, your wudu (ablution) is broken if you sleep:
- lying flat on your back or front
- on your side
- leaning on a wall, pillow or person so heavily that you would fall if it were moved, with your seat lifting off the ground
Your wudu stays if you nod off sitting cross-legged or on a chair with your seat firm, if you sleep standing, or if you doze in ruku or sajdah while keeping the normal posture of prayer. Light drowsiness, where you still hear what people around you say, is not sleep at all.
Common cases: falling asleep on the sofa lying down breaks wudu. Dozing upright in the masjid during a Jumuah talk does not, as long as you did not slump over. If you are unsure whether you slept deeply, a fresh wudu is the safer choice. See how to make wudu for the steps.
The evidence
Sunan Abi Dawud 203
Graded hasan... وكاء السه العينان فمن نام فليتوضا ...
"The eyes are the drawstring of the back passage, so whoever sleeps should make wudu."
Links the ruling to the loss of control in sleep, which is why posture matters.
Where the ruling is recorded
- al-Hidaya, Kitab al-Taharat, chapter on what breaks wudu. Sleep lying down, on the side, or leaning so that one would fall breaks wudu.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Taharah, nawaqid al-wudu. Details the postures of sleep that do and do not break wudu.
- al-Mughni (Ibn Qudama), Kitab al-Taharah, chapter on what breaks wudu. Sets out the positions of the four schools on sleep.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.