Super-sleeper

Supersleepers are the undisputed stars of Babyville. They're the invants who fall asleep happily, independently, consistently.

Source: wiktionary

They still go through stages when she wakes up on the early side, but in general she's a 'supersleeper,' going to bed at 7:00 p.m. and staying asleep for twelve solid hours.

Source: wiktionary

Catherine lost her supersleeper status after complex shoulder surgery two years ago.

Source: wiktionary

As we saw in the last lesson, research has revealed the existence of 'super-sleepers'– people who can fall asleep whenever they want, enjoy the most pleasant of dreams, wake up feeling totally refreshed, and are especially happy, productive, successful, and healthy.

Source: wiktionary