"If the Messenger of Allah ﷺ wanted to sleep while he was Junub, he would perform Wudu' as for prayer before sleeping."  

إِنَّ رَسُولَ اللَّهِ ﷺ كَانَ إِذَا أَرَادَ أَنْ يَنَامَ وَهُوَ جُنُبٌ تَوَضَّأَ وُضُوءَهُ لِلصَّلاَةِ قَبْلَ أَنْ يَنَامَ  

"O Messenger of Allah! May any one of us sleep while he is Junub?" He said: "When he performs Wudu'."  

يَا رَسُولَ اللَّهِ أَيَنَامُ أَحَدُنَا وَهُوَ جُنُبٌ قَالَ إِذَا تَوَضَّأَ