Sleep Loss and Circadian Misalignment - Mechanisms of Insulin Resistance
Washington State University
Summary
The purpose of this study is to examine the impact of timed cortisol release or differently timed cortisol rhythms on insulin resistance in both men and women undergoing sleep restriction. Chronic sleep loss is highly prevalent, affecting 1 in 3 adults in the US. Chronic sleep loss causes stress which induces insulin resistance and leads to obesity and type 2 diabetes. Many factors contribute to sleep loss including shift work, environmental disturbances, sleep/circadian disorders and comorbid medical and mental health conditions. Sleep loss increases the stress hormone cortisol in the evening and decreases daytime testosterone. Examining these hormones in a controlled laboratory environment under different sleep schedules may help researchers find solutions for adults experiencing negative health consequences related to chronic sleep loss.
Description
Sleep loss causes stress, induces insulin resistance (IR) and leads to obesity and type 2 diabetes mellitus (T2D). Sleep loss is highly prevalent, affecting 1 in 3 adults in the USA. Many factors contribute to sleep loss including extended work hours, night shift work, environmental disturbances, sleep/circadian disorders and comorbid medical and mental health conditions. Sleep loss induces changes that typify the autonomic stress response, increases the stress hormone cortisol in the evening, and decreases daytime testosterone. The investigators discovered that preventing cortisol and testost…
Eligibility
- Age range
- 18–45 years
- Sex
- All
- Healthy volunteers
- Yes
Inclusion Criteria: 1. Must be between 18-45 years old. 2. Has a BMI of 18-25 kg/m2 stable weight over the previous 6 weeks. 3. 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 4. No current medical or drug treatment (to include steroids or hormones of any type including c…
Interventions
- DrugMetyrapone And Hydrocortisone
Cortisol will be clamped with oral administration of Metyrapone, which blocks endogenous cortisol biosynthesis. A loading dose of 3,000mg will be given at 10:00 on day 2. Every 4 hours throughout the sleep restriction and sleep deprivation phases, 500mg will be administered beginning at 14:00 on day 2 and ending with a dose at 18:00 on day 5. Using a subcutaneous pump, hydrocortisone is administered here as physiological replacement, with pulses every 3 hours beginning at 10:00 on day 2. Participants assigned to the misaligned cortisol rhythm condition will receive: lowest doses (0.5mg) at 22:00 and 01:00; moderate doses (2.3mg) at 13:00, 16:00, and 19:00; and highest doses (4.0mg) at 04:00, 07:00, and 10:00. An oral 25mg dose of hydrocortisone will be given at the end of the constant routine period to prevent any future hypocortisolemia associated with the hormone clamp.
- DrugDextrose
The frequently sampled intravenous glucose tolerance test is performed before and after sleep restriction, and is widely used and validated. This procedure requires intravenous administration of dextrose, 300 mg/kg as a bolus at time zero. Insulin (0.03 units/kg/min) will be slowly infused intravenously over a 5 minute period from 20 to 25 minutes. Few side effects are anticipated as both doses of glucose and insulin should result in a high, but physiological peak. Administration of insulin as 5-min infusion for clinical studies (rather than bolus) reduces the max concentrations achieved. It is not uncommon for glucose to dip below fasting glycemia at some point after the insulin administration. The concentration at the nadir depends on the subject's insulin sensitivity. Return to fasting level is a function of the waning of the insulin effect (incorporated into the minimal model) as well as counterregulation (which depends on the concentration at the nadir). This can be addressed,
- Druginsulin
Location
- Sleep and Performance Research CenterSpokane, Washington