Irregular sleep and visceral obesity linked to high BP for adolescents
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Visceral adipose tissue plus circadian misalignment — delayed and irregular sleep midpoints — is associated with increased blood pressure among adolescents, according to a study published in Hypertension.
“Circadian misalignment in adolescence, understood as having a delayed sleep pattern on school days or a highly irregular sleep-wake cycle through the week, contributes to the association between obesity, particularly visceral obesity, with elevated BP,” Julio Fernandez-Mendoza, PhD, DBSM, associate professor at the Penn State Sleep Research and Treatment Center, told Healio. “The role found for circadian misalignment is independent of how many hours of sleep adolescents get, which is a known risk factor for obesity-related cardiovascular morbidity.”
Fernandez-Mendoza and colleagues analyzed data from 303 youths who participated in the Penn State Child Cohort at age 5 to 12 years from 2002 to 2006 and returned for an adolescent visit at age 12 to 23 years between 2010 and 2013 (median age, 16.2 years; 52.5% male). DXA scans were conducted to measure visceral adipose tissue. Systolic and diastolic BP were measured. Participants wore an accelerometer the week following the follow-up visit for 7 consecutive nights and completed sleep logs. Sleep duration was calculated as the mean sleep duration across the 7 nights. Sleep variability was defined as the standard deviation in total sleep duration across the week and sleep midpoint was the mean midpoint of the sleep period.
Sleep irregularity, more visceral fat linked to higher BP
Significant interactions were observed between visceral adipose tissue and sleep irregularity on systolic BP (P = .007) and diastolic BP (P = .022). There were 179 adolescents with high sleep irregularity of 45 minutes or more per night. Among those participants, each 1 standard deviation increase in visceral adipose tissue was associated with a 5.67 mm Hg increase in systolic BP (P < .001) and a 3.39 mm Hg increase in diastolic BP (P < .001).
Of the cohort, 194 participated in the study during school and 109 were on break from school. Among participants who were in school, significant interactions were observed between visceral adiposity and sleep irregularity on systolic BP (P = .005) and diastolic BP (P = .003). Among 115 participants with high sleep irregularity while in-school, each standard deviation increase in visceral adipose tissue was associated with a 6.57 mm Hg increase in systolic BP (P < .001) and a 3.33 mm Hg increase in diastolic BP (P < .001).
There was no interaction observed between visceral adipose tissue and weekday sleep midpoint on systolic or diastolic BP, but interactions were observed when only examining weekdays. For 133 adolescents in school who had a sleep midpoint of 2 a.m. or later on weekdays, each one standard deviation increase in visceral adipose tissue increased systolic BP by 4.93 mm Hg (P < .001) and diastolic BP by 2.32 mm Hg (P = .004). Researchers also observed a significant interaction between visceral adipose tissue and the difference in sleep midpoint from weekdays to weekend on systolic BP for participants who were in school (P = .004). Adolescents in school who had a difference in sleep midpoint of less than 30 minutes had a 7.94 mm Hg increase in systolic BP with each one standard deviation increase in visceral adipose tissue (P = .001).
“It was unexpected to find that certain adolescents had a rather low degree of social jetlag, understood as the difference between weekends (when adolescents sleep later and catch up on sleep) and weekdays (when they have set social and academic schedules),” Natasha Morales-Ghinaglia, graduate student at the Penn State Sleep Research and Treatment Center, told Healio. “We dug deeper to find that those with little social jetlag was because they were already sleeping late during school days, thus, their association with worse BP.”
Screening for circadian misalignment important
Fernandez-Mendoza said the findings emphasize the need for adolescents with obesity to be screened for circadian misalignment.
“Clinical evaluations of the sleep-wake pattern should account for adolescents’ different life scenarios, such as during the school year when they have to obey school start times and extracurricular obligations or while on break when they more freely can follow their endogenous or preferred timing of sleep,” Fernandez-Mendoza said. “Taking these scenarios into account helps clinicians uncover distinct forms of circadian misalignment, such as pure delayed sleep phase, high sleep irregularity and social jetlag.”
Morales-Ghinaglia said longitudinal study is needed to assess the long-term impact of the associations observed in the study. A follow-up of the Penn State Child Cohort is planned to take place when the cohort is aged 20 years and older.
For more information:
Julio Fernandez-Mendoza, PhD, DBSM, can be reached at jfernandezmendoza@pennstatehealth.psu.edu.
Natasha Morales-Ghinaglia, can be reached at nmorales@pennstatehealth.psu.edu.
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