Consumption of tobacco and alcohol tied to premature deaths among people who keep awake at night

Finland: A 37-year follow-up in Finnish adults showed a small (9%) rise in the all-cause mortality in people who stay awake at night (night owls) compared to people of definite morning type. 

Findings published in the journal Chronobiology International implied that staying awake late at night has minimal influence on the lifespan of individuals characterized as "night owls." 

Data analysis from a comprehensive study involving approximately 23,000 twins indicates that individuals classified as evening types exhibit a slightly higher mortality risk than morning types. However, this elevated risk is predominantly associated with smoking and drinking habits.

Over a span of more than 37 years, a study conducted in Finland meticulously monitored individuals, emphasizing the significance of considering lifestyle factors.This pertains to the examination of the health implications associated with chronotype, which refers to an individual's innate inclination to sleep at specific times.

According to Dr. Christer Hublin, an author affiliated with the Finnish Institute of Occupational Health in Helsinki, the results of our study indicate that chronotype has minimal or no standalone impact on mortality.

Moreover, the heightened mortality risk observed among individuals characterized as definite "evening" types seems to be primarily attributable to higher tobacco and alcohol consumption, in contrast to those who are unmistakably "morning" types.

A growing body of evidence suggests that both the duration and quality of sleep, as well as night shift work, have an impact on overall health. Previous studies have established a correlation between being a night owl and an elevated risk of various health conditions, particularly cardiovascular problems.

In 2018, data derived from the UK Biobank study, which followed individuals for a period of 6.5 years, revealed that individuals classified as evening types exhibit a slight elevation in the risk of mortality from all causes, including diseases and heart conditions.

The motivation for the current study stemmed from the aforementioned earlier research, as the authors aimed to explore certain factors that were not previously measured. Specifically, they sought to analyze the impact of alcohol consumption and smoking quantity, in addition to assessing their status alone.

Led by Dr. Jaakko Kaprio from the Finnish Twin Cohort study at the University of Helsinki, the recently conducted research tracked a cohort of 22,976 men and women who were 24 years old between the years 1981 and 2018.

At the commencement of the study, the twins were presented with four response options regarding their chronotype: "I am unequivocally a morning person," "I am somewhat a morning person," "I am unequivocally an evening person," and "I am somewhat an evening person."

In 2018, the researchers conducted a follow-up with the participants to determine whether any of them had passed away. This assessment was performed by cross-referencing the data provided by nationwide registers.

The authors considered various factors including education, daily alcohol consumption, smoking status and quantity, BMI (Body Mass Index), and sleep duration as part of their analysis.

The results indicated that out of the twins included in the study, 7,591 individuals were classified as "to some extent" evening types, while 2,262 individuals were categorized as "definite" evening types. On the other hand, the figures for morning types were 6,354 and 6,769, respectively.

Night owls, when compared to morning types, were found to be younger in age and had a higher tendency to consume more alcohol and smoke. Furthermore, individuals classified as definite evening types were less likely to report obtaining a recommended 8 hours of sleep.

Out of all the participants, a total of 8,728 individuals had passed away by 2018. The analysis revealed that the likelihood of mortality from any cause was approximately 9% higher among individuals classified as definite night owls compared to those categorized as early birds.

Nevertheless, the study's findings underscored that the main contributors to these deaths were smoking and alcohol consumption rather than chronotype. This observation was emphasized by the fact that non-smokers did not exhibit an elevated mortality risk.

The causes of deaths associated with alcohol included alcohol-related diseases as well as accidental alcohol poisoning.

Dr. Kaprio highlights that their findings can be more readily extrapolated to the general population than the UK Biobank study. The health status of their participants closely mirrored that of the overall population. In contrast, the participants in the UK Biobank study exhibited a higher level of healthiness compared to the average population.

The researchers emphasized the strength of their study in having access to comprehensive data on various lifestyle factors. However, it is important to note that the findings were based on self-reported data obtained by asking a single question.

Reference:

Christer Hublin, Jaakko Kaprio, Chronotype and mortality-a 37-year follow-up study in Finnish adults, Published, 15 Jun 2023, https://doi.org/10.1080/07420528.2023.2215342