Introduction:
Insufficient sleep is widely prevalent among US adults and is a risk factor for type 2 diabetes (T2D). Experimental studies show adverse effects of acute, severe short sleep on insulin sensitivity, but it is unclear whether these reflect risks associated with milder short sleep routinely observed in the general population. To date, no study has evaluated the impact of prolonged mild sleep curtailment on markers of insulin resistance in women or whether these effects differ by menopausal status, known to impact insulin sensitivity.
Hypothesis:
Glucose and insulin levels, as well as a measure of insulin resistance (HOMA-IR), will increase during 6 wk of sleep restriction (SR) relative to adequate sleep (AS). Adverse effects of prolonged short sleep will be exacerbated in postmenopausal women.
Methods:
Thirty-four women (age: 38±14 y; BMI: 25.6±3.6 kg/m2; n=10 postmenopausal) with adequate habitual total sleep time (TST) (453±33 min) took part in a randomized crossover study with two 6-wk phases: AS and SR. In AS, participants were asked to maintain stable nightly bed and wake times determined from 2 wk of screening with wrist actigraphy and sleep logs. In SR, bedtime was delayed to reduce TST by approximately 1.5 h/night. Sleep was measured continuously using actigraphy and verified weekly for compliance. At wk 0, 3, 4, and 6 fasting blood samples were collected. Outcomes included glucose and insulin levels as well as HOMA-IR scores, calculated from those values. Linear-mixed models tested interactions of sleep condition with week on outcome measures in the full sample and by menopausal status.
Results:
Sleep condition impacted the change in TST from baseline (P<0.0001), which was reduced in SR and unchanged in AS (-79±6 vs -4±6min). In the full sample, there was no sleep condition by week interactions for glucose (P=0.67), insulin (P=0.14), or HOMA-IR (P=0.16). Similar results were observed in premenopausal women (all P>0.50). However, in postmenopausal women, there was a significant effect of sleep condition on change in insulin (P=0.046) and HOMA-IR (P=0.039) over the 6 wk. In SR, insulin (slope: 0.26±0.28 μU/mL) and HOMA-IR (slope: 0.07±0.08) increased, while AS resulted in reductions in these outcomes (insulin slope: -0.56±0.29 μU/mL; HOMA-IR slope: -0.16±0.08).
Conclusions:
We provide the first evidence that chronic short sleep, even if mild, adversely affects insulin sensitivity in postmenopausal women. In contrast, maintenance of AS may improve glycemic regulation. Interestingly, prolonged short sleep did not impact markers of insulin resistance in premenopausal women; further investigation into these life-stage related differences, including underlying mechanisms, is warranted. Results suggest that, in postmenopausal women, a group at heightened risk of poor sleep and T2D, achieving adequate sleep may be an effective strategy to improve cardiometabolic health.
The use of hyaluronic acid and polymethylmethacrylate in the skin aging process in a comparative analysis (the advantages, disadvantages and adverse effects of each filler)
