Hormonal Mechanisms of Sleep Restriction - Axis Study

Sleep restriction increases evening cortisol and decreases testosterone. These are the main catabolic and anabolic hormones in men, respectively. This catabolic-anabolic imbalance likely leads to metabolic and reproductive ill-health. The hypothalamic-pituitary-end organ (adrenal or testis) mechanisms that must underpin these changes are unknown. This study will administer drugs to clamp the function of each of these nodes to determine the regulatory changes that have occurred with sleep restriction. Even though the study is randomized order in design, the main comparison is before and after sleep restriction under each of these clamp conditions. Participants are admitted to the chronobiology laboratory where they are given 1 night of 10 hours sleep opportunity, followed by 4 nights of 4 hours sleep opportunity. Up to 80 participants (assuming twenty different participant for each of the 4 clamp conditions) can be enrolled. However, participants will be allowed an opportunity to be randomized to all 4 conditions so that as few as 20 participants may be required. Urn randomization will be used to ensure that 20 different participants are involved in each of the 4 conditions.

Inclusion criteria

• Men aged 22-45 years
• Willingness to provide written informed consent
• Stable weight over preceding 6 weeks
• Body Mass index (BMI) 20-28 kg/m2

Exclusion criteria

• Unable or unwilling to provide IRB (Internal Review Board)-approved informed consent
• Clinical disorders and/or illnesses
• Current medical or drug treatment, as assessed by questionnaire
• History of brain injury or of learning disability - Vision or hearing impairment unless corrected back to normal
• Anemia (Hct <38%)
• History of psychiatric illness
• Clinically significant abnormalities in blood and urine, and free of traces of drugs
• Other endocrine abnormalities including hypothyroidism or adrenal failure; primary gonadal disease as indicated by serum LH (luteinizing hormone) or FSH (follicle stimulating hormone) concentration >10 or >15 IU/L, respectively, hyperprolactinemia indicated by prolactin >25ug/L
• Type 2 Diabetes (HgbA1C)
• Current smoker
• Recent or concurrent drug or alcohol abuse
• Blood donation in previous eight weeks
• Travel across time zones within one month of entering the study
• Sleep or circadian disorder
• Shift work within three months of entering the study
• Irregular bedtimes (not between 6 and 10 hours in duration)
• Unoperated obstructive uropathy, recurrent prostatitis, indeterminate prostatic nodularity, Hx or Suspicion of cancer of the prostate gland or PSA (prostate-specific antigen) >4ng/ml
• Previous adverse reaction to sleep deprivation or any of the drugs to be administered
• Concurrent participation in another research study