Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates regarding Sayyiduna Umar (may Allah be pleased with him) that he asked the Prophet Muhammad (peace and blessings be upon him): Can a person sleep in a state of janabah (major ritual impurity)? The Prophet Muhammad (peace and blessings be upon him) replied: Yes, if he wishes, he may perform wudu (ablution) and then (sleep).
Hadith Referenceصحیح ابن حبان / كتاب الطهارة / 1216
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - المصدر السابق: م نحوه.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط مسلم.