Causes and Diagnoses

Causes and Diagnoses of Circadian Rhythm Sleep Disorders

Those with a circadian rhythm sleep disorder have an inadequate ability to reset their sleep/wake cycle in response to environmental time cues. Therefore, their biological clocks are set earlier than the general population, so they naturally go to bed and wake earlier.

Without regular environmental time cues, such as sunrise, sunset or a daily routine, individuals can have an internal rhythm imbalance that causes this sleep disorder.


Several tests may be used to diagnose circadian rhythm sleep disorders, which are characterized by disrupted sleeping and waking times. Your specialist will review your symptoms, take your medical history and perform a physical exam, if needed. Your sleep medicine specialist may also use these diagnostics:

Northwestern Medicine offers on-campus facilities dedicated to sleep disorders. These facilities earned American Academy of Sleep Medicine accreditation—considered the gold standard—from the largest professional medical society for clinicians and researchers in the field of sleep medicine.