From Longman Dictionary of Contemporary Englishearly/late riserearly/late riserWAKE UP/GET UPsomeone who usually gets out of bed very early or very late → riser
Examples from the Corpus
early/late riser• A red squirrel was another early riser.• The restaurants are late risers as well.• There was the possibility of kingfisher and water rail for early risers on the morrow.• It will be particularly useful for early risers who once had to endure deafening music from Benidorm bars until the small hours.• Graduate students in most institutions are notoriously late risers, who work way past conventional bedtime.• At 0630 hours the first of the early risers entered the cookhouse for breakfast.• By the evening they are still full of energy when the early risers wilt.• We were early risers on the first morning. 