What are the common circadian rhythm disorders?
- Shift work disorder
- Jet lag
- Free-running sleep disorder
- Irregular sleep-wake rhythm disorder
- Delayed sleep-wake phase disorder
- Advanced sleep-wake phase disorder
We operate on a 24-hour biological sleep-wake clock that is primarily affected by natural light, darkness, and hormone production. This natural body clock is known as the circadian rhythm. Understanding the common circadian rhythm disorders is crucial because aside from inducing feelings of wakefulness and sleepiness, this rhythm also helps regulate hormone production, cell regrowth, body temperature, and digestion.
A person with a healthy circadian rhythm will wake up in the morning feeling energized due to the hormone cortisol and become gradually tired throughout the day. Feelings of sleepiness will start as the sun sets and light fades. The hormone melatonin is produced to induce relaxation.
Meanwhile, circadian rhythm disorders refer to a group of conditions that occur when there is an alteration between the body’s natural body clock and the external environment. While the symptoms may vary from one circadian rhythm disorder to another, these can range from:
- Excessive daytime sleepiness
- Chronic sleep fragmentation
- Social, mental, physical, and occupational performance impairments
Based on the international qualifications of the American Academy of Sleep Medicine (AASM), these are the six common circadian rhythm disorders. Knowing more about them is the key to getting quality sleep and improving all-around health.
Shift Work Disorder
Like millions of employees across the world, if you have a job that starts outside 7 am to 6 pm, you are more likely to develop shift work disorder. In general, shift work disorder primarily affects people who work early morning, night, and rotating shifts.
Working outside normal hours will cause a misalignment in the circadian rhythm. As shift work disorder typically results in losing one to four hours of sleep every 24 hours, it becomes difficult to adjust to the body’s natural sleep-wake cycle. This results in excessive sleepiness, grogginess, difficulty falling asleep/staying asleep, and even an increased risk of accidents.
People with shift work disorders can maintain a regular sleep schedule even during days off, practice good sleep hygiene, or seek professional help for sleeping aid options (i.e., benzodiazepine receptor agonists, melatonin, cognitive-behavioral therapy).
Jet lag occurs when there is a disruption in the circadian rhythm when traveling over time zones. The circadian rhythm is desynchronized and takes longer to adapt to the new time zone. As a result, symptoms like excessive daytime sleepiness, fatigue, and temporary sleep disturbances one to two days after the flight may exhibit.
Jet lag is often more likely to be experienced during eastward travel. For example, you are more likely to feel jet-lagged when traveling to the USA compared to traveling to Asia or Australia. This is because westward travel results in shifting time backward and the day becomes longer. You will find it easier to adjust your circadian rhythm. Meanwhile, northbound and southbound travel doesn’t cause extreme jet lag, making it easier to recover.
For example, when you travel from Australia to the USA, you cross 14 time zones. It will take about 14 days for your circadian rhythm to adjust. Jet lag is not a serious condition but you can re-sync your circadian rhythm faster by regulating your bright light exposure or gradually adjusting your sleep schedule before the flight.
Free-Running Sleep Disorder
Free-running sleep disorder is also known as a non-24-hour sleep-wake rhythm disorder. It occurs when the circadian rhythm does not reset every 24 hours. Here, the natural body clock is not in sync with the natural light and dark cycle. As a result, a person with a free-running sleep disorder will find their normal sleep period constantly shifting, being delayed by minutes to hours.
For example, you might fall asleep at 11 pm one night and sleep at 1 am the next night. Over time, this can worsen until you notice you are sleeping at 4 am or later every night.
The disorder primarily affects people who are completely blind because their circadian rhythm cannot be regulated by the light. Blind individuals are often confused about the time of the day. There is no cure for a free-running sleep disorder, but treatments include melatonin prescriptions and bright light therapy.
Irregular Sleep-Wake Rhythm Disorder
In simple terms, irregular sleep-wake rhythm disorder occurs when there is a desynchronization between the circadian rhythm and the light-darkness cycle. If you have irregular sleep-wake rhythm disorder, then your sleep-wake times show no clear pattern. You stay awake during normal sleeping hours and you feel sleepy during the day.
Most people with an irregular sleep-wake rhythm disorder typically have some form of neurodevelopmental or neurodegenerative condition (i.e., Parkinson’s disease, Alzheimer’s disease, Huntington’s disease). Treatment for this circadian rhythm disorder is aimed at stimulating the body’s sleep-wake cycle. This can include bright light therapy, taking melatonin, and practicing good sleep hygiene.
Delayed Sleep-Wake Phase Disorder
Delayed sleep-wake phase disorder is prevalent among young adults and teens which pushes back their sleep-wake cycles.
If you have delayed sleep-wake phase disorder, you will fall asleep very late at night and have difficulties waking up early in the morning. This may impede early morning tasks such as going to school or work.
Treatment for delayed sleep-wake phase disorder includes practicing good sleep hygiene or sleeping earlier. If your target sleep schedule is 11:00 pm, you should sleep at 10:45 pm on one night, 10:30 pm on the next night, and so on until the desired schedule is reached.
Advanced Sleep-Wake Phase Disorder
Advanced sleep-wake phase disorder is essentially the opposite of delayed sleep-wake phase disorder. It occurs when the person falls asleep earlier and wakes up earlier than the desired time due to signals sent to the brain.
If you have an advanced sleep-wake phase disorder, you might find yourself falling asleep anywhere between 6 pm and 10 pm and waking up between 1 am and 5 am. This results in difficulty staying awake throughout the day.
This condition is prevalent among older adults but treatment plans may come in the form of adopting good sleep hygiene, taking prescription sleeping pills, and engaging in bright light therapy.
These are just some of the common circadian rhythm disorders. As a general rule of thumb, you should seek professional help if you are experiencing sleep disorders. Your doctor will be able to prescribe the right treatments for better slumber and improved everyday productivity.