Abul Juwairiyah (rahimahullah) mentions the following:

I was blessed with the opportunity to spend time in the company of Hammaad bin Abi Sulaimaan (rahimahullah), ‘Alqamah bin Marthad (rahimahullah), Muhaarib bin Dithaar (rahimahullah) and ‘Awn bin ‘Abdillah (rahimahullah). I was also blessed with the opportunity to spend time in the company of Imaam Abu Hanifah (rahimahullah), and I did not find any person who spent his night more excellently than Imaam Abu Hanifah (rahimahullah). I spent six months in his company, and during the entire period of six months, I never once saw him lie down and sleep at night (i.e. every night, he would spend the entire night performing salaah).

(Tabyeedh-us-Saheefah pg. 126)