Whenever the Prophet ﷺ intended to sleep while he was Junub, he used to wash his private parts and perform ablution like that for the prayer.  

كَانَ النَّبِيُّ ﷺ إِذَا أَرَادَ أَنْ يَنَامَ وَهْوَ جُنُبٌ غَسَلَ فَرْجَهُ وَتَوَضَّأَ لِلصَّلاَةِ  

I asked Messenger of Allah ﷺ "Can any one of us sleep while he is Junub?" He replied, "Yes, if he performs ablution, he can sleep while he is Junub."  

أَنَّ عُمَرَ بْنَ الْخَطَّابِ سَأَلَ رَسُولَ اللَّهِ ﷺ أَيَرْقُدُ أَحَدُنَا وَهْوَ جُنُبٌ قَالَ نَعَمْ إِذَا تَوَضَّأَ أَحَدُكُمْ فَلْيَرْقُدْ وَهُوَ جُنُبٌ  

ʿUmar bin Al-Khattab told Messenger of Allah ﷺ, "I became Junub at night." Messenger of Allah ﷺ replied, "Perform ablution after washing your private parts and then sleep."  

أَنَّهُ قَالَ ذَكَرَ عُمَرُ بْنُ الْخَطَّابِ لِرَسُولِ اللَّهِ ﷺ أَنَّهُ تُصِيبُهُ الْجَنَابَةُ مِنَ اللَّيْلِ فَقَالَ لَهُ رَسُولُ اللَّهِ ﷺ تَوَضَّأْ وَاغْسِلْ ذَكَرَكَ ثُمَّ نَمْ  

The Prophet ﷺ used to visit all his wives in one night and he had nine wives at that time.  

أَنَّ نَبِيَّ اللَّهِ ﷺ كَانَ يَطُوفُ عَلَى نِسَائِهِ فِي اللَّيْلَةِ الْوَاحِدَةِ وَلَهُ يَوْمَئِذٍ تِسْعُ نِسْوَةٍ