Losing one hour of sleep per night may not seem alarming, but a recent study suggests that this small change could affect weight and daily activity levels within a few weeks.

Researchers found that reducing sleep duration by about one hour and 20 minutes daily for six weeks was linked to weight gain, increased sitting time, and decreased physical activity, according to a study published in the Annals of Internal Medicine and reported by mindbodygreen.

Daily habit that may increase your weight - illustrative (iStock)

Real-life experiment

To simulate what many people experience in daily life, the researchers did not ask participants to stay up all night but instead gradually delayed their bedtime so that each lost about 80 minutes of their usual sleep each night.

The study included 95 healthy men and women who typically slept between 7 and 8 hours per night. Participants were followed for six weeks, with precise monitoring of sleep patterns and physical activity using wearable devices, along with measurements of weight, waist circumference, body composition, and some biomarkers related to metabolism.

The researchers also explained that the goal was not to test the effects of severe sleep deprivation but to see whether a small, persistent sleep deficit—the most common among workers and students—could have a noticeable impact on health.

Daily habit that may increase your weight - illustrative (iStock)

Influential factor

Moreover, the results revealed that participants who slept less gained on average about half a kilogram during the study period compared to those who maintained their usual sleep duration.

Researchers also noted that they became less active during the day, with sitting time increasing by about 17 minutes daily, while this increase was greater among men and postmenopausal women, approaching 30 minutes daily.

The study team noted that these changes may seem limited when viewed individually, but they could become a significant factor in weight gain if sustained for months or years, especially with a gradual decline in physical activity.

Daily habit that may increase your weight - illustrative (iStock)

Affects multiple pathways

The findings did not stop at weight gain; researchers noted that previous studies on the same participants showed that chronic sleep deprivation, even if mild, was associated with reduced insulin sensitivity in some women, along with inflammatory markers linked to increased risk of heart disease over time.

Researchers also hypothesized that lack of sleep affects multiple pathways in the body, potentially altering the balance of hunger and satiety hormones, reducing energy levels, making a person less inclined to move and more likely to eat larger amounts of food.

The study team emphasized that the results do not mean losing an hour of sleep will automatically lead to weight gain in everyone, but they provide additional evidence that adequate sleep is an essential part of maintaining health, just like a balanced diet and physical activity.

The researchers concluded that many people focus on diet and exercise when trying to lose weight, while regulating sleep schedules may be one factor that does not receive enough attention, despite its clear impact on the body over time.

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