Wrapping the Guru Granth Sahib in cloths and carrying it to a separate room for the night treats the scripture in a manner otherwise reserved for a living person retiring to rest, a deliberate extension of the belief that the volume is not merely a text to be read but the continuing embodied presence of the Guru, which is also why the closing hymns recited at Sukhasan, the Kirtan Sohila, are the identical hymns an individual Sikh recites privately each night before sleep, applying to the scripture the same nightly devotional closing an ordinary person applies to their own day.
The most elaborate version of this nightly rite is performed at the Harmandir Sahib, the Golden Temple in Amritsar, where each night the volume is carried in procession from the main shrine to a separate building, the Akal Takht, accompanied by singing and a formal palanquin, and carried back again each morning in the reverse direction, a nightly procession that has continued in this specific form for a very long period and draws visitors specifically to witness it. Ordinary gurdwaras perform a simpler version of the same closing without the procession or crowd, moving the volume only as far as an adjoining room reserved for the purpose, but the underlying gesture, treating the scripture's daily cycle as mirroring a living being's waking and resting, is consistent across every scale at which the rite is performed.