I generally tent so it does not matter so much what I sleep in. and in cold weather I generally sleep in pants and shirt anyway so if I get up in the middle of the night it does not matter. But in hotter weather I would likely sleep in boxers and may not even be entirely covered by a light quilt. Is that acceptable in a shelter or do people sleep in clothes all night and /or dress inside their bag if they need to get up in middle of night? How similar or different is it at a hostel?