Scientists in Russia are proposing that there are four sleep chronotypes, as opposed to the standard two of larks and owls, as reported by The Atlantic.
For a study forthcoming in the journal Personality and Individual Differences, biologist Arcady Putilov and his colleagues at the Siberian Branch of the Russian Academy of Sciences asked 130 people to stay awake for 24 hours. The subjects filled out questionnaires about how awake they felt, their sleep patterns, and how well they had functioned during the previous week.
