Why does the Qur'an describe sleep as rest and the night as a covering?

Answer

Verses 78:9–11 say Allah "made your sleep a rest (subāt), made the night a covering (libās), and made the day for livelihood (maʿāsh)." The commentators explain subāt as a cessation of activity and a recovery for the body from the day's exertion; al-Saʿdī describes it as a stilling of movement that restores strength. The night is called libās — literally a garment — because its darkness wraps and conceals people the way clothing covers the body, giving quiet and privacy for rest, as al-Ṭabarī and al-Qurṭubī note. The day, by contrast, is maʿāsh: the bright, active time appointed for seeking provision and earning a living. Together these describe the natural rhythm of human life — rest and recovery during the dark, exertion and provision during the light. This pairing aligns well with what we now understand about circadian biology, where sleep restores the body and activity tracks the light cycle, though the Qur'an presents it as a designed mercy rather than a scientific claim. The verses invite gratitude and reflection: the God who ordered day and night for our benefit is the God who controls all of existence.