Bhagavad Gita: Regulation of diet and sleep (Dhyana-yoga (Text 16 Ch 6))

Sri-bhagavan uvaca

naty-asnatas 'tu yoga 'sti
na caikantam anasnatah
na cati-svapna-silasya
jagrato naiva carjuna

Meaning: There is no possibility of one's becoming a yogi, O Arjuna, if one eats too much or eats too little, sleeps too much or does not sleep enough.

Bhagavad Gita: Regulation of diet and sleep (Dhyana-yoga (Text 16 Ch 6))