People who experience repeated bouts of circadian misalignment, such as shift workers, are at higher risk of cardiovascular disease (CVD) and Type 2 diabetes (T2D) compared to daytime workers. However, the mechanism(s) by which shift work and associated circadian misalignment increase CVD and T2D risk are unknown. This project will examine whether elevated plasma lipids are a mechanism by which circadian misalignment impairs vascular function, insulin sensitivity, glucose homeostasis and muscle lipid accumulation, which could be targeted to prevent and treat cardiometabolic disease in people who chronically experience circadian misalignment, which includes more than 20% of the US workforce.
18-65 years old
worked the night shift for the last 1 year or more,
habitually sleep 5-9 hours per 24h period (night shift workers typically experience chronic insufficient sleep),
body mass index (BMI) of 20.0 - 35.0 kg/m2 and weight stable (plus or minus 5% of current body weight in the last 6 months); sedentary to mild physical activity level (less than 2 days of planned exercise per week);
existing diagnosed sleep or eating disorder (e.g. obstructive sleep apnea [OSA], periodic limb movements of sleep [PLMS], narcolepsy, travel more than 1 time zone in 3 weeks before the study; anorexia nervosa, more than one food allergy to maintain flexibility in diet planning);
following any TRE (time-restricted eating) or intermittent fasting plan in the last year;
following any special diet plan, like paleo, keto, gluten-free or vegan, that can affect the primary lipid outcome measures in the last 6 months; any clinically significant surgical condition within the last year;
diagnosed diabetes or cardiovascular disease
Crossover
Time-restricted eating
BehavioralNight shift workers will participate in 4 weeks of fasting during the biological nighttime while remaining awake during overnight work shifts.
Control eating
BehavioralNight shift workers will participate in 4 weeks of Control eating across the daytime and nighttime hours while remaining awake during overnight work shifts.
Blood pressure via 24-hour assessments
Four weeks of TRE during shift work will reduce 24-hour blood pressure versus Control.
Insulin sensitivity via clamp
Four weeks of TRE during shift work will improve insulin sensitivity versus Control.
Cerebrovascular reactivity via transcranial doppler
Four weeks of TRE during shift work will improve cerebrovascular reactvity versus Control.
Muscle lipid accumulation via lipidomics
Four weeks of TRE during shift work will reduce muscle lipid accumulation versus Control.
24-hour blood sampling for lipids, glucose, insulin, and vascular markers
Four weeks of TRE during shift work will improve 24-hour markers of vascular function versus Control.
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Colorado State University
Lead sponsor
University of Colorado, Denver
Collaborator
National Heart, Lung, and Blood Institute (NHLBI)
Collaborator
