This study is about how sleep loss affects your ability to think and changes the helpful bacteria living in your gut. We are also testing how a prebiotic diet alters how you and the bacteria living in your gut respond to sleep loss and being awake at night. This research will help us to create treatments and strategies for people working long hours under stressful conditions at night (e.g., emergency workers and military personnel). We are looking for healthy men and women, aged 18-35, to participate in two laboratory visits of approximately 3.7 days each at the CU Boulder Sleep and Chronobiology Laboratory. Participants will be compensated up to $2,451. For study details, email sleep.study@colorado.edu and ask about the Navy study.