Delayed Sleep Onset Linked to Insulin Resistance in Women

Women who have difficulty falling asleep are more likely to develop insulin resistance leading to Type 2 diabetes, according to results published recently in Sleep Medicine.¹

Using cross-sectional data collected between 2004 and 2009 from the Midlife Development in the United States (MIDUS) II biomarker project, investigators from South Korea and the United States collaborated to evaluate the impact of sleep and inflammatory markers on insulin resistance. The study cohort included 374 community-based participants (138 men and 236 women) in Madison, WI, who agreed to wear a Mini Mitter Actiwatch-64 wrist activity monitor for 1 week while they underwent a sleep study, which included keeping a sleep journal. Objective measurements taken via actigraphy from the Actiwatch included total sleep time (TST), sleep onset latency (SOL), and wake after sleep onset (WASO).

Gender Differences

After 7 days, slight differences were observed between women and men. The women in the study demonstrated greater antidepressant medication use (16.1% vs 8%, respectively, P = .025) and slightly longer TST (6.41 vs 6.12 hours, respectively, P= .007), compared to men, although rates of diagnosed diabetes were similar between the groups (11% vs 10.9%, respectively).

Specific indicators emerged through different analyses that were associated with increased insulin resistance in both genders: univariate analysis showed a link between higher body mass index (BMI), the presence of diabetes, higher SOL, shorter TST, and inflammatory cytokines, while multivariate regression analysis showed a correlation only to higher BMI, the presence of diabetes, and elevated C-reactive protein (CRP) levels. None of the sleep measures studied correlated with insulin resistance.

Various studies have previously demonstrated gender differences in sleep factors contributing to insulin resistance, which according to the authors may point to a greater vulnerability to sleep disturbances among women that is indicative of higher levels of inflammation.^2-4

Similar Mechanisms

Contrary to previous research showing that duration of sleep is directly related to insulin resistance (primarily in young men),^5-7 the main finding of the current study was that difficulty with sleep onset—which was more common in women—was more significantly associated with insulin resistance than shorter TST, which did not show any correlation.

The authors contend that the current study did, however, support previous findings of hyperarousal of the inflammatory system as a mechanism of insulin resistance, as increased SOL in women was at least partly attributable to an indirect effect of inflammatory cytokines. It also pointed to evidence that sleep onset disturbances, along with other sleep factors, may contribute via multiple mechanisms to insulin resistance in women, and that different factors may produce similar effects in men. The immediate implications are that improvements in sleep onset for women may help reduce risk of Type II diabetes.

References

1. Kim TH, Carroll JE, An SK, Seeman TE, Namkoong K, Lee E. Associations between actigraphy-assessed sleep, inflammatory markers, and insulin resistance in the Midlife Development in the United States (MIDUS) study. Sleep. 2016; doi: 10.1016/j.sleep.2016.07.023.
2. Suarez EC. Self-reported symptoms of sleep disturbance and inflammation, coagulation, insulin resistance and psychosocial distress: Evidence for gender disparity. Brain Behav Immun. 2008;22:960–8.
3. Irwin MR, Carrillo C, Olmstead R. Sleep loss activates cellular markers of inflammation: Sex differences. Brain Behav Immun. 2010;24:54–7.
4. Prather AA, Epel ES, Cohen BE, et al. Gender differences in the prospective associations of self-reported sleep quality with biomarkers of systemic inflammation and coagulation: Findings from the Heart and Soul Study. J Psychiatr Res. 2013;47:1228–35.
5. Pyykkonen AJ, Isomaa B, Pesonen AK, et al. Sleep duration and insulin resistance in individuals without type 2 diabetes: The PPP-Botnia study. Ann Med. 2014;46:324–9.
6. Darukhanavala A, Booth JN, 3rd, Bromley L, et al.Changes in insulin secretion and action in adults with familial risk for type 2 diabetes who curtail their sleep. Diabetes Care. 2011;34:2259–64.
7. Javaheri S, Storfer-Isser A, et al. Association of short and long sleep durations with insulin sensitivity in adolescents. J Pediatr. 2011;158:617–23.