'Night owls' more likely to die younger, study says. But the problem isn't sleep.

Morning larks have been found to live longer than night owls, according to research. However, a new report suggests that this may be less related to sleep and more connected to lifestyle choices during wakeful hours.

Finnish researchers conducted an analysis of data from over 20,000 individuals who participated in a sleep habits survey in 1981. The study, published in the peer-reviewed journal Chronobiology International, revealed that approximately 29% of respondents identified as morning people, almost 28% as "somewhat" morning people, 33% as "somewhat" evening people, and nearly 10% as evening people.

The study authors discovered that self-proclaimed night owls had a higher likelihood of premature death compared to morning people, even after accounting for factors such as age, sex, ethnicity, body mass index, sleep duration, socioeconomic status, and health issues. The mortality risk increased by 21% for individuals who identified as evening types and 9% for those who were "somewhat" evening types.

However, once smoking and drinking were taken into consideration, the increased risk largely disappeared. The researchers found that the mortality risk among night owls was primarily associated with smoking and alcohol consumption, with a higher occurrence of deaths related to alcohol-related diseases and poisonings in the evening type group.

Previous studies had suggested that the higher risk of early death among night owls was due to insufficient sleep. However, since the researchers considered sleep duration, the new report highlights the significant role that lifestyle factors play.

Jennifer Martin, a professor of medicine at the University of California, Los Angeles, and former president of the American Academy of Sleep Medicine, who was not involved in the study, explained that the findings emphasize the choices individuals make. She mentioned that being an evening type doesn't necessarily mean engaging in smoking and drinking until the early hours of the morning—it's a matter of personal choice.

The study doesn't provide an explanation for why night owls are more likely to drink and smoke, but Martin suggested that it may be related to the availability of establishments open late at night. She pointed out that late-night activities typically revolve around unhealthy choices, which is how society is structured, as opposed to activities like eating salads and exercising.

Other studies have also linked staying up late with health conditions such as cardiovascular disease and mood disorders. Both excessively short and long sleep durations have been associated with an increased risk of death. However, further research is necessary to fully understand the relationship between sleep and health consequences, according to Dr. Yo-El Ju, a neurologist at Washington University's Sleep Medicine Center.

"Circadian rhythms are closely tied to sleep patterns, making it difficult to separate the effects of circadian rhythms, sleep, and health behaviors."