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

Umar ibn al-Khattab asked the Messenger of Allah ﷺ, “May one of us sleep while he is in a state of janabah (major ritual impurity)?” He said: “Yes. When one of you performs wudu, let him sleep while he is in a state of janabah.”

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