Circadian Rhythm

A circadian rhythm (/sərˈkeɪdiən/), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (is endogenous) and responds to the environment (entrained by the environment).


Cluster Number:
Wiki Number: W042
Diagnosis: Circadian Rhythm Sleep Disorder
US Patients:
World Patients:
Sex Ratio:
Age Onset:
Brain Area: suprachiasmic nucleus
Symptoms: falling asleep in daytime; biological clock misaligned with circadian rhythm.
Causes: intrinsic: delayed, advanced, irregular or blindness; extrinsic: shift–work, jet-lag; Alzheimer’s often destroys patterns
Medications: None listed.
Therapies: chronotherapy-delay to normalize; light therapy; hypnotics; melotonin in evening; dark therapy


The world-wide medical research
reports chosen for each diagnosis 

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PubMed article’s summary-abstract.

  • Cushing's disease: risk of recurrence following trans-sphenoidal surgery, timing and methods for evaluation
    by Maria Balomenaki on May 17, 2022

    The treatment of choice for Cushing's disease (CD) is trans-sphenoidal surgery (TSS). However, TSS is not always curative and, even when curative it is associated with a substantial rate of recurrence. Published recurrence rates vary between 5 and 20%; half of these recurrences appear within 5-years and the remaining half within or even after 10 years post-surgery. A low or undetectable cortisol in the immediate post-op period is regarded as the best criterion of remission. However, low post-op...

  • Circadian Rhythm Sleep Disorders: Genetics, Mechanisms, and Adverse Effects on Health
    by Chaoran Liu on May 16, 2022

    Nearly all living organisms, from cyanobacteria to humans, have an internal circadian oscillation with a periodicity of approximately 24 h. In mammals, circadian rhythms regulate diverse physiological processes including the body temperature, energy metabolism, immunity, hormone secretion, and daily sleep-wake cycle. Sleep is tightly regulated by circadian rhythms, whereas a misalignment between the circadian rhythms and external environment may lead to circadian rhythm sleep disorders (CRSD)....

  • Melatonin as a Potential Neuroprotectant: Mechanisms in Subarachnoid Hemorrhage-Induced Early Brain Injury
    by Chengyan Xu on May 16, 2022

    Subarachnoid hemorrhage (SAH) is a common cerebrovascular disease with high mortality and disability rates. Despite progressive advances in drugs and surgical techniques, neurological dysfunction in surviving SAH patients have not improved significantly. Traditionally, vasospasm has been considered the main cause of death and disability following SAH, but anti-vasospasm therapy has not benefited clinical prognosis. Many studies have proposed that early brain injury (EBI) may be the primary...

  • Brief Developmental Exposure to Fluoxetine Causes Life-Long Alteration of the Brain Transcriptome in Zebrafish
    by Amin Nozari on May 16, 2022

    Fluoxetine (FLX) and other selective serotonin reuptake inhibitors are widely used to treat depressive disorders during pregnancy. Early-life exposure to FLX is known to disrupt the normal function of the stress axis in humans, rodents, and teleosts. We used a zebrafish line with a cortisol-inducible fluorescent transgene to study the effects of developmental daily exposure to FLX (54 µg/L) on the transcriptomic profile of brain tissues in exposed larvae and later as 6-month-old adults. High...