Specialist Advice — 9 minutes

Circadian rhythm disorder: causes, symptoms and treatments

March 11, 2026

Sleep care team
Sleep care team
info@biron.com

Do you find yourself falling asleep before the evening even begins, only to wake up before dawn? And no matter what you try, adjusting your sleep schedule feels impossible? When your sleep no longer follows the natural cycle of day and night, you may be experiencing a circadian rhythm disorder.

person sleeping in bed

What is a circadian rhythm disorder?

Most people naturally wake up with daylight and fall asleep once it gets dark. This natural cycle is regulated by the circadian rhythm, a true internal biological clock located in the hypothalamus, a region of the brain. The circadian rhythm also influences several biological functions, such as blood pressure, body temperature, and mood [1].

A circadian rhythm disorder occurs when this internal clock becomes shifted or out of sync with social or environmental demands. This disruption leads to significant impairment in sleep and daytime functioning.

Causes

Sleep disorders related to the circadian rhythm are caused by an occasional or ongoing disruption of sleep patterns. This disruption can result from internal factors, such as brain damage or hormonal changes, or from external factors (environmental and behavioural) such as:

  • Excessive screen use in the evening
  • A festive nightlife
  • Jet lag
  • Hospitalization or bed rest
  • A lack of exposure to natural light or blindness
  • Night shifts or variable hours
  • Certain medications

Consequences

People with a circadian rhythm disorder sleep at inappropriate times or struggle to maintain a consistent sleep schedule. The result: excessive daytime fatigue, nighttime insomnia… and sometimes much more.

A disrupted biological clock can also interfere with body temperature regulation and hormone production, which can negatively affect overall quality of life. Out of sync with a normal sleep-wake cycle, affected persons may sometimes have to deprive themselves of sleep in order to meet their social or professional obligations. For example, an adolescent who always goes to bed late because of a circadian rhythm disorder may have to get up early for school, reducing their total sleep time. This sleep debt is often the cause of severe fatigue, a higher tendency to take risks, a loss of concentration, attention and energy and mood disorders.

Recent studies suggest that circadian rhythm disruption may also be associated with mental health problems, such as depression, anxiety and bipolar disorder [1, 3, 4].

What are the types of circadian rhythm disorders?

Delayed sleep phase syndrome: This disorder is more common in adolescents and young adults. It is characterized by a misaligned sleep schedule, meaning that falling asleep and waking up occur more than two hours after the normal cycle (e.g., 3 a.m. and 10 a.m.). The person may have a normal quality and quantity of sleep, but has difficulty falling asleep and waking up at times that are compatible with daily obligations.

Advanced sleep phase syndrome: This disorder is more common in the elderly . Falling asleep and waking up occur much earlier (at least two hours, often more) than the normal schedule. Although they may have a normal amount and quality of sleep, people with this disorder have difficulty staying awake early in the evening (from 6 p.m. to 9 p.m.) and wake up early (from 2 a.m. to 5 a.m.).

Irregular sleep-wake syndrome: This disorder is characterized by variable sleep periods. Sleep is fragmented into short periods throughout the day and night. Overall, the person may get a normal amount of sleep, but the fragmented nature of the sleep can be disruptive and affect their social life. It more often affects the elderly, especially in nursing homes where they have little exposure to time cues such as natural light, daily activities and structured schedules.

Free-running syndrome: This disorder, also known as hypernycthemeral syndrome, causes falling asleep and waking up to be continuously and progressively out of sync with the normal cycle by about 15 minutes. The sleep-wake pattern is not tied to the 24-hour cycle, but to a slightly shorter or longer period. This means that affected individuals fall asleep and wake up a little earlier or later each day. This disorder is more common among blind people because daylight usually helps regulate the sleep-wake cycle.

How is a circadian rhythm disorder diagnosed?

Often confused with other sleep disorders, such as insomnia, circadian rhythm disorders can be difficult to diagnose and often require a consultation with a sleep specialist. To diagnose a circadian rhythm disorder, a doctor may recommend keeping a sleep diary, undergoing a sleep study, an actigraphy assessment or completing other diagnostic tests [5, 6, 7].

What treatments are available?

Treatments for circadian rhythm disorders depend on the type of disorder and its severity. Most treatment plans include a combination of approaches, the most common of which are the following:

Lifestyle changes: This approach aims to improve sleep by adjusting certain lifestyle habits, such as increasing exposure to natural daylight, establishing a consistent daily routine, planning naps or using eye masks. The goal is to develop a good sleep hygiene.

Light therapy: It involves exposure to a very bright lamp that mimics natural daylight (from 1,500 to 10,000 lux depending on the type of light). The duration of the treatment depends on the devices used, and the timing of exposure during the day varies based on the specific type of circadian rhythm disorder. This therapy is particularly beneficial for shift workers, helping to regulate their disturbed circadian rhythm.

Our insomnia Treatment and Recharge (pediatric) programs help identify whether light tharapy is needed and provide clear instructions on how to use it effectively.

Medication: Melatonin, taken in low doses at specific times, may be recommended to treat certain circadian rhythm disorders, including delayed sleep phase syndrome and free-running syndrome. It works by helping to resynchronise the sleep–wake cycle.

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Conclusion

Circadian rhythm disruption can significantly affect not only sleep, but also the physical and mental health of those affected. Seeing a sleep specialist is essential for an accurate diagnosis and appropriate treatment plan, helping improve quality of life, alertness, and the synchronisation of the sleep–wake cycle.

This article was reviewed by health professionals with expertise in sleep health.

For professional support, we’re here.

We offer services that can assist your doctor in diagnosing sleep disorders and determining the appropriate treatment.

Do you have a medical prescription for one of these tests? Book an appointment online or contact Biron Health Group’s customer service at 1 833 590-2712.

Sources8
  1. INSERM. « Chronobiologie. Les 24 heures chrono de l’organisme ». https://www.inserm.fr/dossier/chronobiologie/. (Accessed on April 10, 2025)
  2. ICSD-3-TR International classification of sleep disorders, third edition, text revision, American Academy of Sleep Medecine (AASM). (Accessed on March 3, 2025)
  3. Yong, Yun Min et al. « Causal dynamics of sleep, circadian rhythm, and mood symptoms in patients with major depression and bipolar disorder: insights from longitudinal wearable device data”. https://www.thelancet.com/action/showPdf?pii=S2352-3964%2824%2900129-4. (Accessed on April 10, 2025)
  4. Pallesen, Stale, et al. « Prevalence of Shift Work Disorder: A Systematic Review and Meta-Analysis », Frontiers in Psychology, 23 mars 2021. DOI: 10.3389/fpsyg.2021.638252
  5. Taillard, Jacques et Eric Mullens. « Les outils validés pour le diagnostic des troubles du rythme circadien veille-sommeil (TRCVS) chez les adultes et enfants », La Presse Médicale, vol. 47, nos 11-12 (1re partie), pages 977-981, 2018. DOI: 10.1016/j.lpm.2018.10.017
  6. Mayo Clinic. “Delayed Sleep Phase”. (Accessed on April 10, 2025).
  7. Circadian Rhythm Disorders - What Are Circadian Rhythm Disorders? | NHLBI, NIH
  8. Clinical Practice Guideline for the Treatment of Intrinsic Circadian Rhythm Sleep-Wake Disorders: Advanced Sleep-Wake Phase Disorder (ASWPD), Delayed Sleep-Wake Phase Disorder (DSWPD), Non-24-Hour Sleep-Wake Rhythm Disorder (N24SWD), and Irregular Sleep-Wake Rhythm Disorder (ISWRD). An Update for 2015 | Journal of Clinical Sleep Medicine | Springer Nature Link (Accessed on february 27, 2026).
Sleep care team
Sleep care team
info@biron.com