Whenever Messenger of Allah ﷺ went to bed, he used to blow on his hands while reciting the Mu'auwidhat ( i.e. Suratal-Falaq 113 and Surat-an-Nas 114) and then pass his hands over his body.  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ إِذَا أَخَذَ مَضْجَعَهُ نَفَثَ فِي يَدَيْهِ وَقَرَأَ بِالْمُعَوِّذَاتِ وَمَسَحَ بِهِمَا جَسَدَهُ