sleepyhead; oversleeper
A mildly teasing noun for someone who habitually sleeps late or oversleeps. Often used in casual, friendly contexts.
See also: 寝坊
He's a real sleepyhead, and it's a struggle to wake him up every morning.
For a sleepyhead like me, getting up early is impossible.
Standard kanji spelling.
Mixed kanji-kana spelling.
Compound of 寝坊 (ねぼう, 'oversleeping') and the suffix 助 (すけ), which often adds a familiar or slightly teasing tone to personal traits.