This study will test whether biological sex influences how the body responds to circadian misalignment-a mismatch between the internal body clock and the timing of sleep and eating (as can occur with shift work or jet lag). Researchers will examine how circadian misalignment affects appetite regulation (hunger/fullness) and glucose metabolism (blood sugar control), and whether these effects differ between females and males. Findings may help inform more personalized shift work schedules and targeted strategies to reduce metabolic health risks and sex-related differences in clinical care.

This study will examine whether biological sex affects how the body responds to circadian misalignment-a mismatch between a person's internal body clock and their sleep/wake and eating schedule (similar to what can happen with night shift work, jet lag, or frequently changing sleep schedules). Researchers will measure how circadian misalignment influences appetite regulation (such as hunger and fullness) and glucose metabolism (how the body controls blood sugar), and whether these effects differ between females and males.

By identifying sex-specific responses to circadian misalignment, this research may help guide the development of safer, more personalized shift work schedules and targeted strategies to reduce metabolic health risks, with the goal of improving clinical care and reducing sex-related differences in metabolic disease risk.

Inclusion Criteria:

• 18-40 years of age
• Body Mass Index 18.5-24.9 kg/m2
• Non-smokers, no current tobacco or e-cigarette use
• Healthy with no acute or chronic medical and psychiatric disorders
• Sex assigned at birth consistent with reproductive anatomy at enrollment (per protocol definition)

Exclusion Criteria:

• History of drug or alcohol dependency
• History of psychiatric illness or disorder
• Pregnant
• No prior gender-affirming hormone therapy and no gonadectomy