Poor sleep and low heart rate variability (HRV) may be diagnostic markers of metabolic syndrome, according to study findings published in Sleep.
Researchers sought to examine the individual and combined effects of poor sleep and reduced HRV on metabolic syndrome. Data for this analysis were sourced from 966 adults who participated in the MIDUS II biomarker project, which investigated “biopsychosocial pathways that contribute to physical and psychological health outcomes.” Participants were selected on the basis of Pittsburgh Sleep Quality Index (PSQI) scores, signs and symptoms of metabolic syndrome, and HRV data.
Spearman correlation was used to assess the relationship between global PSQI scores, HRV indices, and individual components of metabolic syndrome. The individual and combined effects of poor sleep and low HR on the odds of metabolic syndrome were evaluated via separate multivariable logistic regression models. Models were fit using global PSQI scores, individual HRV measures, and interactions between individual measures of sleep and HRV.
Among participants included in the analysis, the mean age was 54±11 years, 55% were women, 92% were White, and 66% were married.
Metabolic syndrome was noted in 36% of the participants. The odds of meeting the criteria for metabolic syndrome increased by 7% for every 1-unit increase in global PSQI score. Participants with global PSQI scores above 5 had a 58% increased odds of meeting the criteria for metabolic syndrome.
Further analysis of the relationship between global PSQI score and metabolic syndrome was performed after stratification by HRV status; results varied according to the specific HRV measure evaluated. For participants with low HRV levels, there was an association between global PSQI score and metabolic syndrome. The greatest odds of metabolic syndrome were detected among participants with both low HRV levels and high PSQI scores (>5).
Factors associated with metabolic syndrome within strata of low-frequency HRV or standard deviations of the RR interval included poor sleep quality, latency, and duration; sleep disturbance; and daytime dysfunction.
Study limitations include the cross-sectional design, the predominance of White participants, and the lack of objective sleep measures.
“These findings highlight the potential for targeting both HRV and sleep to non-invasively reduce or prevent cardiometabolic and related chronic diseases,” the researchers concluded.
Nevels TL, Wirth MD, Ginsberg JP, McLain AC, Burch JB. The role of sleep and heart rate variability in metabolic syndrome: evidence from the Midlife in the United States (MIDUS II) Study. Sleep. Published online February 2, 2023. doi:10.1093/sleep/zsad013