Are you more of an early riser or a night owl team? This apparently trivial question could turn out to be much more important than we think, for health at least. Studies have been coming for a long time to highlight the advantages and disadvantages of going to bed early or late, with sometimes bizarre revelations. Still, if we focus on health, physical and mental, it seems that night owls have every interest in bringing their bedtime forward.
We know the importance of the duration and quality of sleep, but bedtime and wake-up times can also have an impact on the health and well-being of populations. A factor which is of great interest to scientists around the world, increasing research to determine the consequences, whether positive or negative, of going to bed early or on the contrary late. Some have even gone so far as to draw parallels between bedtime and intelligence quotient, creativity, and even income level. Night owls are therefore likely to have lower incomes, according to Finnish researchers. And this would not be the only drawback if we rely on the studies carried out on the subject.
Increased risk of diabetes
A study published in the journal Annals of Internal Medicine recently reignited the debate on bedtime. Work carried out by researchers at Brigham and Women’s Hospital suggests that the evening chronotype, which corresponds to going to bed and waking up late, is associated with a less healthy lifestyle and an increased risk of diabetes. To achieve these results, scientists analyzed data from 63,676 nurses, collected between 2009 and 2017, integrating numerous parameters such as chronotype, diet, body mass index, tobacco and alcohol consumption, physical activity, or a history of diabetes. They then compared these data to those concerning diabetes monitoring from self-assessments and medical records.
Result: people considered to be night owls and late risers were more likely to develop type 2 diabetes, with an increased risk of 72% before taking into account other lifestyle factors, and 19 % after consideration of these parameters. The researchers also observed a greater propensity to consume alcohol, and in greater quantities, to eat unhealthily, to smoke, and to sleep less, among night owls. “When we controlled for unhealthy lifestyle behaviors, the strong association between chronotype and diabetes risk was reduced but remained“said the lead author of the study.
Between 10 p.m. and 11 p.m. for heart health
What is the ideal bedtime to reduce the risk of heart disease? This is the question that a team of British researchers tried to answer, whose work was published in 2021 in the European Heart Journal – Digital Health. “The body has an internal 24-hour clock, called the circadian rhythm, which helps regulate physical and mental functioning. Although we cannot conclude causality from our study, the results suggest that earlier or later bedtimes may be more likely to disrupt the body clock, with adverse consequences for cardiovascular health.“, explained Dr David Plans, of the University of Exeter, one of the authors of this work.
As you will have understood, it is not a question here of being an early person or a night owl to preserve your heart health, but of adopting a very specific bedtime. After analyzing data from more than 88,000 people aged 43 to 79, recruited between 2006 and 2010 (falling asleep and waking up times via an accelerometer and cardiovascular monitoring), the researchers suggested that bedtime should take place between 10 p.m. and 10:59 p.m. to reduce the risk of developing cardiovascular disease. They said the risk was 25% higher when night owls fell asleep at midnight or later, and 24% higher when early owls fell into the arms of Morpheus before 10 p.m.
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A link with anxiety disorders
Bedtime could also impact mental health, or at least be associated with high levels of stress and anxiety. This is what researchers from Binghamton University, in the United States, showed in 2014. Published in the journal Cognitive Therapy and Research, their work focused on a restricted panel of 100 young adults who completed a battery of questionnaires and completed computerized tasks, then reported whether they were morning or evening workers. At the end of their research, the scientists concluded that people who slept less and went to bed later were more likely to be overwhelmed by negative thoughts, and this in a repetitive manner, than those who did not.
“Ensuring that sleep is obtained at the right time of day may be an inexpensive and easily disseminated intervention for people bothered by intrusive thoughts“, the main authors of the study said in a press release. And added: “If further findings confirm the relationship between sleep pattern and repetitive negative thoughts, it could one day lead to a new avenue of treatment for people with internalizing disorders“.
Note that there is no direct causal relationship here between bedtime and anxiety levels, the latter being able to cause men and women to fall asleep later and influence quality of sleep. But bedtime could play a role in treating certain disorders.
