Good sleep habits are important for overweight adults, study finds

Circadian rhythms, the body's internal biological clock, regulate sleep-wake cycles and metabolic processes. Emerging research underscores their profound impact on health, particularly in relation to weight regulation and cardiometabolic diseases.

Disruptions in these rhythms, whether from lifestyle habits or external factors, can lead to significant health challenges, with recent findings highlighting nuanced differences between men and women.

Recent studies have established a strong correlation between late sleep timing and elevated body mass index (BMI), independent of sleep duration. However, much of this research lacks direct measurement of biological circadian markers, such as melatonin levels.

Late sleep timing may disrupt weight regulation through various pathways, including reduced sleep duration due to occupational or social demands, barriers to healthy lifestyle choices, and misalignment of the circadian rhythm.

Circadian misalignment occurs when sleep-wake cycles deviate from the body's natural rhythm. This misalignment can contribute to metabolic and behavioral changes, such as impaired glucose metabolism and altered appetite hormones.

Shift workers, who often experience extreme circadian disruptions, face heightened risks of obesity, diabetes, and heart disease. Yet even minor misalignments, such as those caused by jet lag or irregular sleep schedules, can affect health outcomes.

One way to assess circadian alignment is by measuring the "phase angle," which is the duration between the onset of melatonin production (dim light melatonin onset, or DLMO) and sleep onset. A short phase angle, where sleep begins soon after melatonin production starts, may indicate misalignment.

Studies have found that individuals with shorter phase angles tend to experience higher depressive symptoms, though associations with physical health outcomes are less understood.

Inconsistent sleep schedules, such as those seen in social jet lag—when sleep patterns differ significantly between workdays and weekends—may further exacerbate circadian misalignment. Research suggests that such inconsistencies are linked to higher BMIs, though the role of circadian timing in these outcomes requires further exploration.

A study from Oregon Health & Science University (OHSU) provides new insights into the relationship between circadian rhythms, sleep habits, and health. Published in The Journal of Clinical Endocrinology & Metabolism, the research recruited 30 overweight or obese participants, evenly split between men and women, to examine how sleep timing relative to DLMO impacts health.

Participants provided saliva samples at regular intervals to pinpoint their melatonin onset. They then recorded their sleep habits over a week.

Researchers categorized participants into two groups: those with a narrow phase angle (short duration between melatonin onset and sleep) and those with a wide phase angle (longer duration). A narrow phase angle indicated individuals staying awake beyond their internal biological clock's natural signals, which was associated with poorer health outcomes.

The study revealed significant gender-specific differences in health metrics among participants with narrow phase angles. Men in this group exhibited higher levels of abdominal fat, triglycerides, and overall metabolic syndrome risk scores. In contrast, women showed increased overall body fat percentages, glucose levels, and resting heart rates.

“It was somewhat surprising to see these differences present themselves in a sex-dependent manner,” noted Andrew McHill, Ph.D., senior author and assistant professor at OHSU. “It’s not one size fits all, as we sometimes think in academic medicine.”

The findings emphasize the need to consider gender-specific approaches to addressing sleep and circadian disruptions. According to lead author Brooke Shafer, Ph.D., improving sleep practices, such as reducing screen time and aligning bedtime with natural tiredness, can support better overall health.

Shift workers, who often face extreme circadian misalignment due to overnight schedules, are a population of particular concern. The OHSU team plans to extend their research to explore sex-specific differences in populations experiencing more severe sleep disruptions. “We want to figure out possible interventions that keep this vital core group of the workforce healthy,” Shafer explained.

For the broader population, the study underscores the importance of maintaining consistent sleep schedules and aligning sleep patterns with natural circadian rhythms. While individual differences in circadian alignment can arise from factors like age, sex, and lifestyle, reducing circadian misalignment is a key strategy for promoting metabolic health.

Obesity and cardiometabolic diseases are growing public health challenges. This research highlights the complex interplay between circadian rhythms and health, offering new directions for interventions.

By addressing circadian misalignment through lifestyle adjustments or tailored medical approaches, it may be possible to mitigate some of the risks associated with poor sleep habits and disrupted biological rhythms.

As the scientific community continues to unravel the connections between circadian rhythms and health, these findings reinforce the importance of aligning daily behaviors with the body's natural clock.

From reducing social jet lag to managing shift work schedules, fostering circadian alignment offers a promising path toward better health outcomes.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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