Do Early Birds and Night Owls Have Different Personalities?

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When the end of the day arrives, early birds are winding down for the evening. By contrast, night owls are just getting started. This difference in “chronotype” has deep roots in our evolutionary history. With groups made up of members with varying chronotypes, there would have been people on the lookout for danger at all hours of the day and night. But research reveals that the differences between morning and evening types amount to more than just bedtime preferences: A sizable body of evidence has also found that individuals with different chronotypes also differ on key personality characteristics.

This relationship between chronotype and personality was the focus of a study conducted by Christoph Randler and Lena Saliger of the University of Heidelberg. To test whether early birds and night owls showed personality differences, the investigators began by assessing participants for chronotype, as well as temperament and character. One measure determined whether participants were a morning type, an evening type, or neither. Another questionnaire evaluated participants on a range of personality characteristics, including novelty seeking, harm avoidance, persistence, reward dependence, self-directedness, cooperativeness, and self-transcendence, or a tendency toward spirituality and idealism). The researchers then performed a correlational analysis of the data.

The results were striking:

• Morning types showed higher levels of cooperation, while evening types were lowest. This result is in keeping with prior research linking morningness to the personality trait of agreeableness.
• Evening types reported greater novelty seeking than "neither" types, and neither types scored higher on novelty seeking than morning types. The relationship between novelty seeking and eveningness, the authors contend, may have to do with low dopamine levels — and may act as a risk factor for addictive behaviors, like smoking. According to research, evening types drink more alcohol and smoke more cigarettes compared to morning types.
• Morning types were highest on persistence, while evening types were lowest on this characteristic. The authors point out that these findings are consistent with other research — for example, morningness has been linked to both conscientiousness and proactivity. Similarly, morningness has been found to be negatively related to indecision and procrastination. Taken together, these results shed light on why morning types manage academic responsibilities more easily, and get better grades. Along similar lines, eveningness has been linked to increased impulsivity as well as higher measures of ADHD.
• Evening types were higher on self-transcendence than "neither" types. This finding is in line with studies linking eveningness to creative thinking. Similarly, eveningness also correlates with the trait of openness, albeit weakly. The authors maintain that openness, creativeness, and self-transcendence may be related to each other, as well as to eveningness.

While we no longer have to be on guard for threats around the clock like our ancestors, the evolutionary legacy of chronotypes remains a fascinating facet of human psychology in modern life.