Astanga Hrudaya
यथाकालमतो निद्रां रात्रौ सेवेत सात्म्यतः। असात्म्याज्जागरादर्धं प्रातः स्वप्यादभुक्तवान्॥६५॥
Hence, the person should sleep at the proper time at nights daily as much as desirable and become habituated to it. If he has kept awake at night due to non-habituation (not accustomed to), he should sleep for half that period, the next morning without taking any food.
english translation
yathAkAlamato nidrAM rAtrau seveta sAtmyataH। asAtmyAjjAgarAdardhaM prAtaH svapyAdabhuktavAn॥65॥
hk transliteration by Sanscript