Circadian Rhythm Disorders Types
The types of circadian rhythm disorders are advanced or delayed sleep-wake phase disorder, irregular or non–24-hour sleep-wake rhythm disorder, and shift work or jet lag disorder. The type you may have is based on your pattern of sleep and wakefulness.
To better understand circadian disorders, read our How Sleep Works health topic.
Advanced sleep-wake phase disorder
If you have advanced sleep-wake phase disorder (ASWPD), you may find it very difficult to stay awake in the early evening and as a result, wake up too early in the morning. This can interfere with work, school, or social responsibilities.
Delayed sleep-wake phase disorder
This is one of the most common circadian rhythm disorders. If you have delayed sleep-wake phase disorder (DSWPD), you may fall asleep later than you would like and then find it difficult to wake up on time in the morning. Delayed sleep-wake phase disorder often interferes with work, school, or social responsibilities. You may get too little sleep, which can lead to daytime tiredness or anxiety.
Irregular sleep-wake rhythm disorder
If you have irregular sleep-wake rhythm disorder (ISWRD), you may have several short periods of sleep and wakefulness. You may be unable to sleep during the night and take multiple naps during the day due to excessive sleepiness. You may not feel rested after sleep.
Jet lag disorder
This is often a temporary disorder that may affect you if you travel across at least two time zones in a short period. Your sleep-wake rhythm falls out of sync with the local time at your destination, so you may feel sleepy or alert at the wrong time of day or night. Jet lag disorder is often more severe when you travel east, compared to when you travel west.
Some people experience social jet lag, which can occur when you go to activities on weekends or days off at much later times than you do on weekdays or workdays. This is not considered a disorder.
Non–24-hour sleep-wake rhythm disorder
This type of circadian rhythm disorder occurs when your sleep-wake rhythm is not in sync with the 24-hour day. When this happens, your sleep times may gradually become more delayed. For example, your sleep time may be delayed to the point that you are going to sleep at noon instead of night. This often occurs when light exposure is very limited, and it is common in people who are completely blind. You may have periods of insomnia and daytime sleepiness, followed by periods with no symptoms, when your circadian rhythms happen to align with your environment.
Shift work disorder
Shift work disorder affects those who work during the night or on a rotating schedule. Because of your work schedule, you may not be able to get uninterrupted quality sleep when your body needs it. Shift work disorder can cause insomnia, extreme tiredness, and sleepiness while working at night.