It is narrated from Sayyidah Aishah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) never slept before Isha, nor did he (peace and blessings be upon him) engage in talk after Isha.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2124