It was narrated from Ibn 'Umar, from ʼUmar رضي الله عنه that he asked the Prophet (ﷺ) ﷺ:

Can one of us sleep when he is junub? He said: “He may do wudoo’ and sleep if he wishes.” On one occasion Sufyan said: `Let him do wudoo’ and sleep.`

حَدَّثَنَا سُفْيَانُ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنِ ابْنِ عُمَرَ، عَنْ عُمَرَ، أَنَّهُ سَأَلَ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَيَنَامُ أَحَدُنَا وَهُوَ جُنُبٌ قَالَ يَتَوَضَّأُ وَيَنَامُ إِنْ شَاءَ وَقَالَ سُفْيَانُ مَرَّةً لِيَتَوَضَّأْ وَلْيَنَمْ‏.‏