This protocol will increase sleep duration in participants who maintain less than 6 hours sleep per night, to target the recommended 7 hours of sleep per night. The focus of this study is determine how increasing nightly sleep duration in these individuals who maintain less than 6 hours sleep per night changes their plasma metabolome and insulin sensitivity. The primary outcome will examine changes in branched-chain amino acids and the secondary outcome will examine changes in insulin sensitivity. The investigators will also determine if changes in plasma metabolites can be used as a biomarker to discriminate between adequate versus insufficient sleep.

Impaired sleep affects millions of people each year representing an important public health issue. This project will utilize metabolomics approaches to identify potential mechanisms underlying increased cardiometabolic risk associated with insufficient sleep and to identify potential biomarkers in the blood that respond to insufficient sleep. Investigators will conduct a controlled in-laboratory insufficient protocol where participants will sleep in the lab for one night with sleep timing based on their habitual insufficient sleep schedule. In the morning, plasma will be collected for metabolomics analyses and participants will complete an oral glucose tolerance test for insulin sensitivity analyses. Participants will then complete a 4 -week increased sleep duration intervention targeting the recommended 7 hours of sleep per night. Following this intervention participants will again sleep in the lab for one night on their new sleep schedule. In the morning, plasma will be collected for metabolomics analyses and participants will complete an oral glucose tolerance test for insulin sensitivity analyses. Investigators anticipate these findings will be the first step in developing biomarkers of impaired sleep under free-living sleep conditions, and to determine how such biomarkers relate to insulin sensitivity changes associated with sleep loss.

Inclusion Criteria:

1. 18-35 years old; men and women

   a. Equal numbers of women and men will be included.

2. Body Mass Index (BMI) of > 18.5 and <24.9.

3. Inactive to habitual moderate physical activity level (<5 days of exercise per week).

4. Sleep/wake history: habitual sleep duration less than 6 hours per night.

5. Altitude history: Potential participants must have lived at Denver altitude or higher for at least 3 months.

Exclusion Criteria:

1. Any clinically significant unstable medical or surgical condition within the last year (treated or untreated).
2. Any clinically significant psychiatric condition, as defined by DSM-IV-TR. I
3. Any clinically significant sleep disorder.
4. Use of prescription medications/supplements within one month or need of these medications at any time during the study.
5. Symptoms of active illness (e.g., fever).
6. Uncorrected visual impairment
7. History of shift work in prior year or travel more than one time zone in three weeks prior to study.
8. Participants must be entirely drug-free of illicit drugs, medications, nicotine and herbal products for one month prior to study.
9. Blood donation in the 30 days prior to inpatient study.
10. Ovulating women will be selected on the basis of a history of regular menstrual cycle ranging in length from 25-32 days with a maximum of three days variation month-to-month. They will have no history of prior gynecological pathology, be at least 1 year post-partum, not breast-feeding and not pregnant (HCG pregnancy test at screening and upon admission to the inpatient protocol).

Any data generated from the proposed work that is presented in a peer reviewed journal will be uploaded, de-identified, into the Metabolomics Data Repository and Coordinating Center (DRCC) (U01) through UCSD; http://www.metabolomicsworkbench.org/nihmetabolomics/datasharing.html. In addition, .raw data that is presented in a peer reviewed journal will be archived indefinitely and made available upon request.

Data will become available upon publication in peer-reviewed journals and will be made available indefinitely.

Active membership and username are required to access the raw metabolomics data on Metabolomics Workbench.