Can anyone sleep in the Masjid without the in-charge's permision?
Generally, sleeping in the Masjid is allowed for a traveler, Mu'takif (a person making E'tikaf) or needy. However, if a Masjid's policy is seek approval of it's keeper in advance then it will be necessary to obtain Masjid caretaker's approval first.It will not be permissible to sleep in that Masjid without his approval unless a reasonable and compelling excuse is found.
And Allah knows best.
Mufti Ikram ul Haq
Darul Ifta of Rhode Island
10 Rajab 1431/ June 23 2010