Sleep‑Aligned Overnight Fasting and Cardiometabolic Function

A sleep-wake-aligned extension of overnight fasting was reported to shift several cardiometabolic biomarkers over a short intervention period, without changes in caloric intake.

In a Northwestern Medicine study, investigators used the sleep period to anchor meal timing and lengthen the overnight fast in a way that fit each participant’s schedule. Outcomes highlighted in the report included changes in nighttime cardiovascular patterns during sleep and measures of daytime glycemic response to a standardized challenge.

The study used a 7.5-week protocol in 39 overweight or obese adults aged 36 to 75 years, comparing an extended overnight fast with participants’ habitual overnight fasting pattern. The intervention was sleep‑aligned overnight fasting, with fasting being 13 to 16 hours in the extended-fasting intervention versus a habitual fast of 11 to 13 hours in the control condition. The protocol extended the overnight fast by about two hours and asked participants to dim lights for three hours before sleep and to avoid eating for at least three hours before bedtime.

Reported outcomes centered on nighttime “dipping” patterns and daytime glycemic control. Compared with those maintaining usual routines, participants who finished eating at least three hours before bed were reported to have increased nighttime blood pressure dipping (about 3.5%) and increased heart-rate dipping (about 5%), described as a more pronounced day–night pattern across sleep and waking activity. The report also described better daytime blood-sugar control, framed as a more efficient pancreatic response when participants were challenged with glucose.