Go to Bed at This Time to Live Longer

Why going to Bed Before 10pm is Hurting your Health

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My Longevity Experiment
September 19, 2024

Best Time to Sleep: How Bedtime Impacts Cardiovascular Health

A recent study published by the European Society of Cardiology (ESC) has revealed that the time of night when individuals go to bed significantly affects their cardiovascular health. According to data presented in European Heart Journal - Digital Health, those who fall asleep during a specific time window have a lower risk of developing heart disease compared to those who go to bed earlier or later.

The Impact of Bedtime on Heart Health

The study's lead author, Dr. David Plans, a Senior Lecturer in Organizational Neuroscience at the University of Exeter, stated, "The body has a 24-hour internal clock, called circadian rhythm, that helps regulate physical and mental functioning."

Dr. Plans continued, "While we cannot conclude causation from our study, the results suggest that early or late bedtimes may be more likely to disrupt the body clock, with adverse consequences for cardiovascular health."

While previous studies have largely focused on the link between sleep duration and cardiovascular disease, this research is one of the first to examine the connection between sleep timing and heart health. The researchers utilized objective measurements of sleep onset, rather than relying on self-reported data, to investigate this relationship.

Study Overview

The study involved 88,026 participants from the UK Biobank, a large-scale biomedical database that collects genetic and health information from over half a million individuals in the UK. The participants, who were recruited between 2006 and 2010, had an average age of 61 years, with women representing 58% of the study group.

Sleep onset and wake times were collected using wrist-worn accelerometers over a period of seven days. In addition to sleep data, participants provided demographic, lifestyle, health, and physical assessments and completed questionnaires. The researchers then followed up with the participants over an average period of 5.7 years to monitor for new diagnoses of cardiovascular disease, which included conditions such as heart attacks, heart failure, chronic heart disease, and stroke.

Key Findings

During the follow-up period, 3.6% of the participants (3,172 individuals) developed cardiovascular disease. The incidence of heart disease was highest among those with sleep onset at midnight or later, and lowest among those who fell asleep between 10:00 pm and 10:59 pm.

After adjusting for various confounding factors such as age, sex, sleep duration, and lifestyle variables, the researchers found that:

  • Sleep onset at midnight or later was associated with a 25% higher risk of cardiovascular disease.

  • Going to bed between 11:00 pm and 11:59 pm increased the risk by 12%.

  • Interestingly, falling asleep before 10:00 pm raised the risk by 24%.

Further analysis revealed that women faced a stronger association between sleep timing and cardiovascular risk, with only sleep onset before 10:00 pm showing significance for men.

Expert Insights

Dr. Plans emphasized the importance of aligning sleep onset with the body’s natural circadian rhythm. "Our study indicates that the optimum time to go to sleep is at a specific point in the body's 24-hour cycle, and deviations may be detrimental to health. The riskiest time was after midnight, potentially because it may reduce the likelihood of seeing morning light, which resets the body clock," he explained.

Regarding the stronger impact on women, Dr. Plans remarked, "It may be that there is a sex difference in how the endocrine system responds to a disruption in circadian rhythm. Alternatively, the older age of study participants could be a confounding factor since women's cardiovascular risk increases post-menopause - meaning there may be no difference in the strength of the association between women and men."

He concluded by stating, "While the findings do not show causality, sleep timing has emerged as a potential cardiac risk factor - independent of other risk factors and sleep characteristics. If our findings are confirmed in other studies, sleep timing and basic sleep hygiene could be a low-cost public health target for lowering risk of heart disease."

Improving Sleep Hygiene for Better Health

For individuals who struggle to fall asleep before midnight, there are practical steps to help align sleep with the body's circadian rhythm. Dr. Mathew Walker, a renowned sleep scientist, offers key tips for promoting better sleep. He explains that darkness triggers the release of melatonin, a hormone that helps regulate sleep. As the sun sets and the sky turns shades of red and orange, the body receives a natural signal to prepare for rest. Using blackout curtains or sleep masks can create an environment conducive to melatonin production.

Additionally, Dr. Walker notes that a drop in core body temperature is essential for sleep initiation. "Your body and brain need to drop their core temp by around 1°C (2 to 3°F) to initiate sleep, that’s why it is easier to fall asleep in a cold room than in a hot one," he says.

By ensuring adequate sleep duration of 7 to 8 hours and falling asleep between 10:00 pm and 11:00 pm, individuals can take meaningful steps to protect their cardiovascular health.

Conclusion

This study underscores the importance of not only how much sleep one gets, but when that sleep occurs. Falling asleep during the body’s natural circadian window of 10:00 pm to 11:00 pm may play a crucial role in reducing cardiovascular risk. As more research emerges, sleep timing could become a key factor in public health strategies aimed at preventing heart disease.

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