long sleeper; person who needs a lot of sleep
Refers to someone who naturally requires more sleep than average, often used in contrast to ショートスリーパー (short sleeper).
She's a long sleeper and can't function well unless she sleeps at least nine hours every day.
The amount of sleep needed differs greatly between long sleepers and short sleepers.
Variant with a middle dot; less common but seen in some contexts.
Borrowed from English 'long sleeper'.