The Prophet ﷺ said: Any person who offers prayer at night regularly but (on a certain night) he is dominated by sleep will be given the reward of praying. His sleep will be almsgiving. (Using translation from Abū Dāʾūd 1314)
أَنَّ النَّبِيَّ ﷺ قَالَ مَا مِنَ امْرِئٍ تَكُونُ لَهُ صَلَاةٌ بِاللَّيْلِ فَيَغْلِبُهُ عَلَيْهَا نَوْمٌ إِلَّا كَتَبَ اللهُ ﷻ لَهُ أَجْرَ صَلَاتِهِ وَكَانَ نَوْمُهُ ذَلِكَ صَدَقَةً