Recent research suggests that an irregular sleep schedule in middle-aged individuals is associated with poorer cardiovascular health. Irregular sleep patterns appear to particularly increase waist circumference. These findings are revealed in a joint study by the University of Oulu and the Oulu Deaconess Institute Foundation, Department of Sports and Exercise Medicine.
This is the first large population-based study focusing on middle-aged individuals that used an activity monitor to measure physical activity and sleep patterns. According to the results, physical activity reduced the detrimental association between an irregular sleep schedule and risk factors for cardiovascular diseases such as blood sugar levels, triglyceride levels, or blood pressure.
Independent of the amount of physical activity and time spent in bed, an irregular bedtime was associated with a larger waist circumference in study participants.
“The association was statistically significant, although the differences in waist circumference between those who go to bed regularly and those who go to bed irregularly were not very large.“
Laura Nauha, lead researcher
The study utilized comprehensive research data from individuals born in North Finland in 1966. A total of nearly 3,700 participants took part in the follow-up study at the age of 46. They filled out questionnaires on health and lifestyle and underwent a clinical examination, which included measurements of height, blood pressure, blood lipid levels, and an oral glucose tolerance test. Physical activity and sleep patterns were measured using an activity monitor worn on the wrist.
On average, middle-aged participants went to bed at 11:22 pm, woke up at 7:17 am, and spent an average of 7 hours and 57 minutes in bed. For half of the participants, bedtime, wake-up time, and time spent in bed varied by at least one hour around the weekly average. „It is assumed that the average bedtime of middle-aged individuals allows for an adequate and recommended nighttime sleep duration of 7 to 9 hours. However, it should be noted that a greater variation in sleep patterns refers to a later age,“ Nauha recalls.
Prior population-based studies on sleep patterns and cardiovascular health mainly focused on shift workers. However, factors other than working hours influence sleep patterns. „Since the functioning of an individual’s internal rhythm is based physiologically on approximately 24-hour cycles, the regularity of the sleep pattern from day to day should be considered in addition to the amount of sleep and physical activity. The individual circadian rhythm, regularity. Sleep patterns and physical activity should be given more consideration in health counseling than before,“ Nauha summarizes.
Nauha, L., et al. (2024). Regularity of bedtime, wake time, and time in bed in midlife: associations with cardiometabolic health markers considering physical activity and sitting time. Journal of Activity Sedentary and Sleep Behaviors. doi.org/10.1186/s44167-023-00040-6.