Modeling the cardiometabolic benefits of sleep in older women: exploring the 24-hour day

Abstract

Study Objectives Activities throughout the day, including sleep, sedentary behavior (SB), light-intensity physical activity (LIPA), and moderate to vigorous physical activity (MVPA) are independently associated with cardiometabolic health. Few studies have examined interrelationships between sleep and 24-hour activity and associations with cardiometabolic risk. The objective of this study is to understand how replacing time in SB, LIPA, or MVPA with sleep impacts cardiometabolic risk. Methods Women’s Health Initiative OPACH Study participants (N = 3329; mean age = 78.5 ± 6) wore ActiGraph GT3X+ accelerometers 24 hours/7 days. Adjusted linear regression estimated the relationship between sleep duration and cardiometabolic markers. Separately for shorter (<8 hours) and longer (≥8 hours) sleepers, isotemporal substitution models estimated the cross-sectional associations with cardiometabolic markers with reallocating time in daytime activities to or from sleep. Results Longer sleep duration was associated with higher insulin, HOMA-IR, glucose, total cholesterol, and triglycerides (all p < 0.05). The associations between sleep duration and C-reactive protein, waist circumference, and body mass index (BMI) were U-shaped (both p < 0.05). For shorter sleepers, reallocating 33 minutes of MVPA to sleep was associated with higher values of insulin, HOMA-IR, glucose, triglycerides, waist circumference, and BMI (0.7%–11.5%). Replacing 91 minutes of SB time with sleep was associated with lower waist circumference and BMI (−1.3%, −1.8%). For long sleepers, shifting 91 minutes of sleep to SB was associated with higher waist circumference and BMI (1.3%, 1.4%). Conclusions This is one of the first isotemporal analyses to include objectively measured sleep duration. Results illuminate possible cardiometabolic risks and benefits of reallocating time to or from sleep.

Isotemporal Substitution of Time Between Sleep and Physical Activity: Associations With Cardiovascular Risk Factors in Early Rheumatoid Arthritis

“…As far as we know, there are no previous publications using isotemporal substitution in patients with RA, but during the last decade, the method has been used in other studies to increase knowledge on the relationships between the 24‐hour activity behaviors and CV health (7). In concordance with our results, a recently published study of older women presented a favorable effect on waist circumference and BMI with a reallocation of time from SB to sleep for the subgroup with shorter sleep duration (<8 hours) (47). In a study conducted in 200 000 participants followed up on for 4.2 years, Stamatakis et al revealed lower all‐cause mortality when replacing sitting time with sleep or with physical activity in participants sleeping 7 or fewer hours per day (48).…”

Rest‐activity rhythms and cognitive impairment and dementia in older women: Results from the Women's Health Initiative

“…Physical activity levels measured as total steps per day and total sleep time in hours were derived based on accelerometry data, as previously described. 16,26,27 Physical function was assessed by the Established Populations for Epidemiological Studies in the Elderly short physical performance battery (SPPB). 28 Finally, we derived a variable indicating the number of comorbidities (cancer, cerebrovascular disease, cardiovascular disease, diabetes, frequent falls, depression, osteoarthritis, and chronic obstructive pulmonary disease) among OPACH participants.…”

Mediating effects of lower extremity function on the relationship between night sleep duration and cardiovascular disease risk: a cross-sectional study in elderly Chinese without cardiovascular diseases

“…With increased age, about one-third of the elderly have a night sleep duration that is either too long or too short. 5 Extreme night sleep duration may impair vascular endothelial function by accelerated lipid deposition 6 and may also cause deterioration of the vasculature by adversely affecting muscle strength. 7 Although previous studies have suggested that extreme night sleep duration is related to CVD risk, especially in the elderly, the relationship may be J-shaped, 8 9 U-shaped 10 or neither.…”

“…Higher triglycerides and cholesterol related to lipid deposition appear in long sleepers. 6 Lipid deposition in the large and middle arteries promotes the formation of atherosclerotic plaques, thickening and hardening of arterial walls, narrowing of the lumen, and ultimately leading to ischaemic diseases. In the Fasa Cohort Study, short night sleep duration was associated with a higher predicted risk of CVD, 27 possibly attributable to lower cholesterol and triglyceride levels compared with the subjects in this study.…”