The Undisclosed Perils of Evening Chronotypes: An In-Depth Analysis

A comprehensive analysis involving more than 60,000 nurses demonstrated that individuals who identify as evening chronotypes face a heightened risk for diabetes and are more prone to engage in detrimental lifestyle behaviors.

A large-scale study focusing on middle-aged nurses indicated that those who are evening chronotypes are inclined to lead an overall unhealthy lifestyle, specifically characterized by tobacco use, inadequate sleep, and lack of physical activity. These individuals were found to have a 72 percent elevated risk of developing diabetes.

Recent investigations involving 60,000-plus nurses in their middle age have uncovered that those displaying evening chronotypes, marked by heightened energy levels in the latter part of the day, face an increased risk for diabetes. Such individuals are also prone to unhealthy lifestyle choices, including tobacco use, insufficient sleep, and sedentary behavior, especially when contrasted with their morning chronotype counterparts. However, the researchers note that variables such as profession, level of education, and socioeconomic background of the participants could potentially influence these outcomes. The results of this investigation were published on September 12 in the Annals of Internal Medicine.

Table of Contents

Decoding Chronotype

Chronotype, often referred to as circadian preference, is partly a result of genetic factors and signifies an individual’s predisposition towards earlier or later sleep patterns. Approximately 8% of the general populace exhibits an evening chronotype. It is noteworthy that this has been linked to poor metabolic regulation, disruptions in glycemic control, metabolic disorders, and a higher rate of occurrence and prevalence of type 2 diabetes. However, the exact mechanisms explaining the observed correlation between an evening chronotype and increased risk of diabetes remain unclear.

Comprehensive Study Outcomes

Researchers from Brigham and Women’s Hospital and Harvard Medical School orchestrated a prospective cohort study involving 63,676 nurses between the ages of 45 and 62 who had no previous history of cancer, cardiovascular ailments, or diabetes, spanning from 2009 to 2017.

It was found that subjects with a “definite evening” chronotype had a 54 percent greater likelihood of adopting an unhealthy lifestyle compared to those with a “definite morning” chronotype. Additionally, individuals with an evening chronotype faced a 72 percent elevated risk of developing diabetes during the period of follow-up.

The authors underscore that even after adjusting for all accounted-for lifestyle and sociodemographic variables, this association remained, albeit at a weakened level. They highlight that these findings are confined to those who had not engaged in recent night-shift work. Further research is essential to evaluate the applicability of these conclusions to men, non-White ethnic groups, and different socioeconomic strata. Moreover, variations in generational diet, exercise, and body weight may limit the generalizability of these results to either younger or older cohorts or contemporary times.

Editorial Perspectives

An accompanying editorial penned by researchers from the Harvard T.H. Chan School of Public Health and Harvard Medical School outlines that numerous variables, such as psychological conditions, work nature, and conceivable lifetime alterations to chronotype, could potentially confound the study’s results. They add that the findings suggest that the mismatch between chronotype and work schedule, rather than the chronotype itself, could be a possible underlying mechanism for these outcomes.

The editorial writers argue that this research adds to the accumulating evidence suggesting that reallocating workers with evening chronotypes to night shifts could enhance sleep quality among shift workers and better their metabolic health. In conclusion, they stress the potential advantages of creating standardized methods for the frequent assessment of chronotype throughout an individual’s lifespan.

For additional information on this study, consult “Staying Up Late Tied to Increased Diabetes Risk.”

Reference: “Chronotype, Unhealthy Lifestyle, and Diabetes Risk in Middle-Aged U.S. Women: A Prospective Cohort Study” by Sina Kianersi, DVM, PhD; Yue Liu, MD; Marta Guasch-Ferré, PhD; Susan Redline, MD, MPH; Eva Schernhammer, MD, DrPH; Qi Sun, MD, ScD and Tianyi Huang, ScD, MSc, published on 12 September 2023 in the Annals of Internal Medicine.
DOI: 10.7326/M23-0728

Frequently Asked Questions (FAQs) about Evening Chronotypes and Diabetes Risk

What is the main focus of this comprehensive analysis?

The main focus of the analysis is to examine the relationship between evening chronotypes and the elevated risk of diabetes, as well as tendencies toward an unhealthy lifestyle. The study specifically involved more than 60,000 middle-aged nurses.

Who conducted the research and who were the participants?

The research was conducted by scientists from Brigham and Women’s Hospital and Harvard Medical School. The participants were 63,676 nurses aged between 45 and 62 years, with no prior history of cancer, cardiovascular disease, or diabetes.

What are evening chronotypes?

Evening chronotypes are individuals who feel more energetic and are more active during the later part of the day. These individuals have a natural inclination towards later sleep patterns.

What lifestyle habits are associated with evening chronotypes according to the study?

The study found that evening chronotypes are more likely to engage in unhealthy lifestyle choices, including tobacco use, insufficient sleep, and a lack of physical activity.

How much more likely are evening chronotypes to develop diabetes?

Individuals with an evening chronotype have a 72 percent higher risk of developing diabetes compared to those with a morning chronotype, according to the study.

Are there any limitations or confounding factors mentioned in the study?

Yes, the study mentions that factors such as profession, education level, and socioeconomic status could influence the results. The study is also confined to those who have not engaged in recent night-shift work.

What are the implications of the study’s findings according to the accompanying editorial?

The editorial suggests that the study adds to growing evidence that reallocating evening chronotype workers to night shifts may improve sleep quality among shift workers and enhance their metabolic health. It also points to the potential benefit of developing standardized tools for assessing chronotype throughout a person’s life.

Is the study applicable to other demographic groups?

The researchers note that further investigation is needed to determine whether the findings are applicable to men, non-White racial or ethnic groups, and other socioeconomic classes.

What is the publication date and source of the study?

The study was published on September 12 in the Annals of Internal Medicine. The DOI for the study is 10.7326/M23-0728.