Imperial tombs contain a dedicated hall for enshrining the spirit tablet.
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寝 is a literary/classical character. In everyday speech, 卧室 (wòshì) or 睡觉 (shuìjiào) are used instead. 寝 appears in formal compounds: 寝室 (dormitory), 就寝 (to retire for the night).
Roof radical on top fixes the location: 寝 happens indoors, specifically in a sleeping chamber. The roof anchors a whole house-and-room family — 家 home, 室 room, 安 peace (woman under roof), 宿 lodge.
Left interior is a stylised bed seen sideways — the right half of 床's etymological 爿. Placed under a roof and beside a sweeping-hand action, it gives the literal scene: a bed inside the bedchamber. Same component anchors 床 bed itself.
Upper-right interior is a stylised hand. Together with 冖 and 又 below, the right half of 寝 pictures a person sweeping or tidying the bedchamber — the cleaning-up that precedes lying down to rest.
Middle-right cover stroke sits between hand and another hand, suggesting the bedclothes or canopy being smoothed flat. The cover radical also appears in 写, 军 — anything tucked under something.
Lower-right shows a second hand — the right-hand pictogram. The redoubled hand-imagery in 寝 underscores the physical action of preparing the bed before sleep, distinguishing 寝 (formal, classical 'retire to bed') from plain 睡 'sleep'.