Impact of Circulating and Tissue-specific Lipids on Vascular Function and Insulin Sensitivity in Chronic Night Shift Workers

Inclusion Criteria:

* 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);

Exclusion Criteria:

* 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

  * The prevalence of insomnia in shift workers is fairly high, ranging from 12.8% to 76.4%, which is higher than estimated for the general population. Insomnia itself is associated with elevated neural cardiovascular responsiveness to stress compared to people without insomnia. Thus, since excessive sleepiness and symptoms of insomnia may be present in night shift workers they will not be exclusionary.