Sleep Loss and Circadian Misalignment - Mechanisms of Insulin Resistance

Inclusion Criteria

• Must be between 18-45 years old.
• Has a BMI of 18-25 kg/m2 stable weight over the previous 6 weeks.
• Is physically and psychologically healthy (incl. regular menstrual cycles in women, no clinical disorders and/or illnesses). Women will be studied during the follicular phase of their menstrual cycle.

Menstrual cycle criteria (using PMID 10941950) 18 to 25 years - Cycle variation ≤9 days 26 to 41 years - Cycle variation ≤7 days 42 to 45 years - Cycle variation ≤9 days

• No current medical or drug treatment (to include steroids or hormones of any type including contraceptives), as assessed by questionnaire.
• Has a negative pregnancy test (women), no clinically significant abnormalities in blood and urine, and free of traces of drugs.
• No history of clinically relevant psychiatric illness.
• No previous history of drug or alcohol abuse.
• Not a current smoker.
• No history of brain injury or of learning disability.
• No previous adverse reaction to sleep deprivation, jet lag, shift work or any of the drugs to be administered.
• Not vision or hearing impairment unless corrected back to normal.
• No endocrine disorder (no abnormal thyroid function tests; no abnormal morning blood cortisol; no primary gonadal disease as indicated by serum LH or FSH concentration > 10 or > 15 IU/L, respectively; and no hyperprolactinemia indicated by prolactin > 25 μg/L).
• No sleep or circadian disorder.
• Has good habitual sleep with regular bedtimes (between 6 and 10 hours in duration).
• Not extreme morning- nor extreme evening-type using Horne-Ostberg Morningness-Eveningness criteria.
• No travel across time zones within one month of entering the study.
• No shift work within three months of entering the study.
• No anemia (hematocrit \<38% in men, \<34% in women).
• No blood donation within the previous 8 weeks.
• No concurrent participation in another research study.