Related Experiment Video
Updated: Aug 2, 2026

Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments
Published on: August 8, 2019
Diagnosis and assessment of sleep and circadian rhythm disorders
1University of Pittsburgh School of Medicine, PA 15213, USA.
Abstract:
Sleep and wakefulness are fundamental behavioral and neurobiological states that characterize all higher animals, including human beings. This article presents an overview of the current state of our knowledge concerning the function of sleep and sleep-wake rhythms, the neurobiology of circadian rhythms, how wakefulness and sleep are studied, and the clinical assessment and diagnosis of sleep and circadian rhythm disorders. Major theories of the function of sleep and sleep-wake rhythms are reviewed, including ecological or environmental advantage, physical restoration, optimizing waking function, learning and integration of experience, and survival. The author then reviews what is known about the neurobiology of endogenous circadian rhythms and how they are affected by environmental time cues. How sleep is studied using polysomnography (PSG) is explained, and the PSG characteristics of the three major neurobehavioral states, wakefulness, rapid eye movement (REM) sleep, and non-rapid eye movement (NREM) sleep, are described. Systems of classifying sleep disorders are reviewed, including those of the DSM-IV-TR, the International Classification of Sleep Disorders, and the ICD-10. Methods of assessing sleep complaints are then described, including taking an accurate history from the patient and bed partner, use of sleep history questionnaires and sleep-wake diaries, use of actigraphy, and use of PSG.
Related Concept Videos
Circadian Rhythms and Gene Regulation
Sleep-Wake Cycles
NREM Sleep
NREM sleep comprises four progressive stages that seamlessly merge:
Management of Insomnia
Understanding Sleep
The circadian rhythm, a nearly 24-hour cycle, is deeply influenced by environmental light cues. Light exposure directly affects the hypothalamus, which in turn regulates...
Insomnia
Multiple factors contribute...
REM Sleep Behavior Disorder
RBD is significantly associated with...

