Older age significantly increases risk for cognitive decline. A growing number of older adults (≥ 65 years) experience cognitive decline that compromises immediate and/or long-term health. Interventions to mitigate cognitive decline are greatly needed. Intermittent fasting aligned with innate circadian rhythms is associated with health benefits and improved circadian rhythms; here, we explore impacts on cognition and cardiometabolic outcomes.

We conducted a single-group, pre-/post-pilot study to explore an 8-week prolonged nightly fasting intervention (14 h fasting/night) among adults 65+ years with self-reported memory decline. We explored changes in cognitive function, insomnia, and cardiometabolic risk factors. Intervention engagement/adherence were assessed. The intervention was delivered fully remotely; participants completed their fasting protocol at home and were not required to come into the lab.

In total, 20 individuals signed consent and 18 participants completed the study. Participants were mean age 69.7 years, non-Hispanic White (89%), predominantly female (95%), married (50%), and employed (65%). Paired t-tests indicated an increase in cognitive function (Memory and Attention Phone Screener) (p = 0.02) with a medium effect size (Cohen’s d = 0.58) and a decrease in insomnia (Insomnia Severity Index) (p = 0.04) with a medium effect size (Cohen’s d = 0.52). Changes in BMI or diet quality were not observed. Engagement (66%–77%) and adherence (70%–100%) were high.

These pilot findings suggest that prolonged nightly fasting, targeted to align food intake with circadian rhythms, may improve cognitive function and sleep among older adults. Fully powered, randomized controlled trials to test the efficacy of this non-pharmacological, low cost-to-burden ratio intervention are needed.

Cognitive decline is intricately linked to various factors such as obesity, stress, poor sleep, and circadian rhythm misalignment, which are interrelated in their impact on cognitive health. Irregular food-intake timing further compounds these issues. The practice of prolonged nightly fasting (PNF) may help synchronize food intake with circadian rhythms, potentially mitigating adverse effects of cognitive decline and associated factors.

A pilot nationwide, remotely delivered, 2-arm randomized controlled trial was conducted to assess the 8-week outcomes of cognition, stress, and sleep, after a PNF intervention (14-hr nightly fast, 6 nights/week, no calories after 8 pm) compared to a health education (HED) control condition. Participants were living with memory decline, stress, and obesity and had weekly check-in calls to report fasting times (PNF) or content feedback (HED).

Participants were enrolled from 37 states in the US; N = 58, 86% women, 71% white, 93% non-Latinx, mean (SD) age 50.1 (5.1) years and BMI 35.6 (3.6) kg/m2. No group differences existed at baseline. Linear mixed-effects models were used to compare outcome change differences between groups. Compared to the HED control, the PNF intervention was associated with improved sleep quality (B = −2.52; SE = 0.90; 95% CI −4.30–−0.74; p = 0.006). Perceived stress and everyday cognition significantly changed over time (p < 0.02), without significant difference by group.

Changing food intake timing to exclude nighttime eating and promote a fasting period may help individuals living with obesity, memory decline, and stress to improve their sleep. Improved sleep quality may lead to additional health benefits.