Night Owls Have Shorter Lives, But It’s Not For The Reason You Think

There’s no single secret to good health and longevity. Instead, it involves multiple factors, namely eating nutritious food, exercising regularly, getting enough sleep, and other overarching lifestyle habits. However, small details can lead to larger, seemingly unrelated outcomes. For example, consuming too much caffeine during the day can lead to poor rest and all the negative effects of sleep deprivation —including an increased risk of car accidents. A similar connection is found in a new study comparing the longevity of self-proclaimed night owls and morning larks. [1]

Night Owls and Poor Health

The researchers set out to find what unique but modifiable habits are linked to shorter and longer lifespans. They discovered that those who prefer to be productive in the evenings have a higher association with morbidity compared to those who prefer mornings. Moreover, those with the evening preference had higher rates of heart disease, metabolic diseases, respiratory disorders, diabetes, and mental health struggles. A similar study found that “evening people” tended to have more links to heart disease risk factors such as obesity and smoking.  

In other words, “night owls” are more likely to engage in unhealthy habits like consuming alcohol and tobacco than “morning larks”. 

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Not the Bedtime That Matters

The study lasted for 37 years, analyzing 22,976 Finnish adult twins. And 42.9% identified as “later chronotypes” or “evening types”. The data showed that they were more likely to engage in riskier behavior that could contribute to morbidity — but “burning the midnight oil” itself was not the problem.

“Our findings suggest that there is little or no independent contribution of chronotype to mortality,” says Christer Hublin, a researcher at the Finnish Institute of Occupational Health. Instead, “the increased risk of mortality associated with being a clearly ‘evening’ person appears to be mainly accounted for by a larger consumption of tobacco and alcohol. This is compared to those who are clearly ‘morning’ persons.” [2]

“Later Chronotypes” vs “Earlier Chronotypes”

In 1981, the researchers identified the participants as “later chronotypes” or “earlier chronotypes” (morning people) then followed up in 2018 to analyze the death rates, as well as details like sleep habits, BMI, education, consumption of substances, etc. By that point, 8,728 of the participants had passed away, and the mortality rates of “definite evening types” were higher than morning types. However, “evening types” who didn’t smoke or drink much had no increased risk of dying.

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Healthy and Unhealthy Night Owls

It’s unsurprising that the participants who drank and smoked were more likely to have higher mortality rates, but this study points out the connection between these habits and going to bed late. For some night owls, the only things they are drinking and smoking are tea and scented candles, so they have no increased risk for diseases. But the researchers found that late bedtimes and unhealthy choices often go hand in hand. Plus, sleep deprivation can lead to many poor health outcomes and lifestyles — including addictions to substances like nicotine and alcohol.

“There is a reciprocal relationship between the reward system and circadian system, and the level of alcohol and substance use correlates with the preference to stay up later at night,” write the researchers. 

However, it’s unclear what’s behind the correlation. What came first, the substance usage or the late bedtime? The authors suggest the connection may be a result of the “chronic misalignment between internal physiological timing and externally imposed timing of work and social activities.”

Improving Health Recommendations

As always, there is no cheat code to good health, no one-ingredient cure-all. And factors like adequate sleep cannot be examined in a vacuum. As this study shows, it’s important to examine all of the choices that lead to individual sleep habits to see which details are impactful on overall health (like smoking) and which are less impactful (like bedtimes).

“Given the associations of chronotype with lifestyle factors that are known to increase the risk of premature morbidity and mortality, the independent contribution of chronotype to mortality is of relevance when providing public health recommendations related to sleep and chronotype,” write the researchers.

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