Wordnet 3.0
ADJECTIVE (1)
1. 
 (of sleep) deep and complete; 
- Example: "a heavy sleep"- Example: "fell into a profound sleep"- Example: "a sound sleeper"- Example: "deep wakeless sleep"[syn: heavy, profound, sound, wakeless]
WordNet (r) 3.0 (2006):
wakeless
    adj 1: (of sleep) deep and complete; "a heavy sleep"; "fell into
           a profound sleep"; "a sound sleeper"; "deep wakeless
           sleep" [syn: heavy, profound, sound, wakeless]