The Physiology of Fatigue in Patients With Chronic Liver Disease

Background: \- Fatigue is a common and often disabling symptom in people with chronic liver disease. Its causes are not well understood. Sleep disturbance may play a role in people with cirrhosis, but these factors have not been studied in people with other stages of liver disease. This study will look at the body's circadian rhythms (internal clock) to see if problems with these rhythms can contribute to fatigue. It will look at the causes and mechanisms of fatigue in people with chronic liver disease by comparing people with and without fatigue. Objectives: \- To study reasons for fatigue in people with chronic liver disease. Eligibility: * \Individuals at least 18 years of age who have chronic liver disease. * \Participants with or without fatigue may enroll. Design: * Participants will be screened with a physical exam and medical history. They will have a 2-day inpatient stay for the study. * For the 7 days before the inpatient stay, participants will keep a sleep diary. They will record any caffeine or alcohol consumption, medicines, exercise, and sleep or naps. They will also wear an actigraph to measure their activity levels. * During the inpatient stay, participants will answer questions about fatigue and sleep habits. They will have regular blood tests for 24 hours. Their body temperature will also be monitored. During the night, they will have a sleep study to look at how well or poorly they sleep. * Treatment will not be provided as part of this study.