Medically reviewed by
Dacelin St Martin, MD
Triple board-certified in Sleep Medicine,
Internal Medicine, and Pediatrics.
A Circadian Rhythm Sleep Disorder (CRSD) consists of six conditions where the internal circadian timing system and desired sleep-wake times are not in proper alignment.
The circadian system plays a vital role in regulating our behavioral, mental, and physical health by modulating many physiological systems, including daily rhythms in core body temperature, cortisol, and appetite.
For a body to maintain proper balance, the circadian system must adjust around the 24-hour day cycle.
A properly aligned circadian system increases drive for sleep at night, particularly in the latter half of the night, helping maintain sleep consolidation until normal wake-up time.
Many factors or time cues affect the circadian system, with the most significant being the environmental light-dark cycle. Other less essential time cues are social factors and temperature.
The Dangers of Blue Light
Staying up late watching digital devices that emit blue light, like the television, computer, or cell phone can cause sleeplessness. This blue light mimics the sun’s bright blue light, signaling to your brain that it’s time to be active and alert.
Blue light has the most substantial effect on synchronizing human circadian rhythm. Exposure to low blue light levels and bright light during the night or before bedtime can disrupt the circadian rhythm by suppressing the production of melatonin and increasing nocturnal alertness.
Types of CRSD
Jet lag or Rapid Time Change Syndrome
A key symptom of jet lag is daytime sleepiness brought about by traveling across time zones. Symptoms worsen with each time zone crossed, especially when traveling eastward.
Shift work sleep disorder (SWSD)
Shift work sleep disorder (SWSD) affects those who work at night or frequently rotate shifts. Shift work can create a discord between the time someone works and their circadian rhythm, causing them to get up to 4 hours less sleep than the average person.
Delayed Sleep Phase Syndrome (DSPS)
People with delayed sleep phase syndrome (DSPS) usually fall asleep very late at night. They also struggle to wake up in time for work, school, or social activities. DSPS is especially common in teens and young adults.
Advanced Sleep Phase Syndrome (ASPS)
People with advanced sleep phase syndrome (ASPS) fall asleep and wake earlier than they desire. For example, they might fall asleep between 6 and 9 p.m. and wake up between 1 and 5 a.m. ASPS is especially common in senior citizens.
Non-24-Hour Sleep-Wake Rhythm Disorder (N24)
Patients with non-24-hour sleep-wake rhythm disorder have a biological clock that’s out of sync with a 24-hour day. As a result, the circadian system drives wakefulness at night and sleep during the day, resulting in daytime sleepiness.
Irregular Sleep-Wake Rhythm Disorder (ISWRD)
People with irregular sleep-wake rhythm disorder have a circadian system that fails to consolidate wakefulness and sleep periods. As a result, someone with this disorder will have frequent naps throughout the day, followed by periods of intermittent wakefulness.
- Insomnia (Onset or Maintenance)
- Daytime sleepiness
- Difficulty waking up in the morning
- Inability to concentrate
- Weight gain
CRSD happens when internal sleep-wake rhythms and day-night cycles are chronically out of sync. Underlying conditions that can lead to CRSD include:
- Shift work
- Time zone changes
- Changes in routine, such as staying up late or sleeping in
- Medical problems including Alzheimer’s and Parkinson’s disease
- Mental health problems
- Shift work
- Overseas travel
- Congestive heart failure
- Chronic obstructive pulmonary disease
- Chronic pain
Medications That Can Cause CRSD
- Beta-adrenergic drugs used to treat asthma
- Selective serotonin reuptake inhibitors (SSRI)
A CRSD diagnosis requires a medical evaluation by a sleep specialist who relies on self-reported and objective data collection, using various measures, like:
- Consistent bed and wake times
- Refrain from napping after 3 p.m.
- Stimulus control (only use bed for sleep and intimacy)
- Avoid rigorous exercise 4 hours before bed
- Avoid greasy or spicy food before bed
- Cool and dark sleeping environment
To have a healthy circadian rhythm, you must develop a regularly timed and stable exposure to daily light and darkness.
The management of lighting and the timing of sleep not only ensures the proper alignment of internal circadian rhythms, but it is also imperative for sustaining restorative, high-quality sleep. Types of therapy include:
- Light Therapy – Sleep rhythms are reset by being exposed to prescribed light levels for specific and regular amounts of time
- Sleep Hygiene – Consistent bedtimes and routines, lifestyle changes, and cool and dark sleep environments are incorporated to facilitate sleep
- Medication – Melatonin, stimulants, or sleeping pills can change sleep-wake cycles
It’s essential to understand how environmental factors such as light, traveling, and certain social habits can impact your sleep. This knowledge is a good start for keeping your circadian sleep rhythm on track; however, if you continue to experience severe sleeping problems, take the time to contact your healthcare provider for further evaluation.
- Wyatt JK. Chronobiology. In: Principles and Practice of Pediatric Sleep Medicine, 2nd ed, Sheldon SH, Ferber R, Kryger MH, Gozal D (Eds), Elsevier, Philadelphia 2014. p.25.
- Wahl, S, Engelhardt, M, Schaupp, P, Lappe, C (2019). The Inner Clock-Blue Light Sets the Human Rhythm. Journal of Biopotonics. https://onlinelibrary.wiley.com/doi/full/10.1002/jbio.201900102