It is narrated from Sayyidah Aishah (may Allah be pleased with her) that when the Messenger of Allah (peace and blessings be upon him) intended to sleep while in a state of janabah, he would perform an ablution like the ablution for prayer before sleeping, and when he intended to eat or drink, he would wash his hands, then eat, and drink if he wished.
Something other than this has also been said regarding this chain, and the hadith of al-Aswad from Aishah is more authentic.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 981