Circadian rhythm disorders, also known as sleep-wake cycle disorders, occur when your internal clock, called a circadian clock, is out of sync with your environment. This clock cycles every 24 hours, and these repeating 24-hour cycles are called the circadian rhythm. Your body tries to align your sleep-wake cycle with cues from the environment, such as light, darkness, eating, and physical activity.
What Can Indicate a Circadian Rhythm Disorder?
If your sleep-wake cycle is out of sync with your environment, you may have difficulty sleeping, and the quality of your sleep may be poor. Disruptions that interfere with your daily activities may indicate a circadian rhythm disorder. Disruptions in your sleep patterns can be temporary and caused by your sleep habits, work, or travel. A circadian rhythm disorder can also be long-term and caused by ageing, genetics, or a medical condition. You may experience symptoms such as extreme daytime sleepiness, decreased alertness, and problems with memory and decision-making.
How Do Doctors Diagnose Circadian Rhythm Disorder?
To diagnose a circadian rhythm disorder, your doctor may ask about your sleep habits and suggest a sleep study and other diagnostic tests. Your treatment plan will depend on the type and cause of your circadian rhythm disorder. You can prevent circadian rhythm disorders by making healthy lifestyle changes to improve your sleep habits. If left untreated, circadian rhythm disorders may increase the risk of certain health problems or lead to workplace and road accidents.
What Are the Different Types of Circadian Rhythm Disorders?
Circadian rhythm disorders are a group of sleep disorders that affect the natural sleep-wake cycle. There are different types of circadian rhythm disorders, each with distinct symptoms and causes. Below are some of the most common types of circadian rhythm disorders.
Advanced Sleep-Wake Phase Disorder (ASWPD)
If you have ASWPD, you may find it difficult to stay awake in the early evening, which can result in waking up too early in the morning. This can interfere with work, school, or social responsibilities.
Delayed Sleep-Wake Phase Disorder (DSWPD)
This is one of the most common circadian rhythm disorders. If you have DSWPD, you may fall asleep later than you would like and have difficulty waking up on time in the morning. DSWPD 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 (ISWRD)
If you have 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.
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 at 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.
What Raises Your Risk of Circadian Rhythm Disorders?
Circadian rhythm disorder can be caused by several factors. Age, genetic predisposition, occupation, lifestyle habits, and medical conditions can all increase an individual’s risk of developing the disorder. Hormonal changes during certain stages of life can also affect an individual’s susceptibility to the disorder.
How Circadian Rhythm Disorder Can Affect Your Health
Circadian rhythm disorders can have a negative impact on your health if left untreated. They can increase your risk of developing various health conditions, such as a weakened immune system that can cause infections and slow recovery from illnesses. Cardiovascular diseases like atherosclerosis or stroke can also be a result of circadian rhythm disorders. Cognitive and behavioural disorders can occur, leading to decreased attention, vigilance, concentration, motor skills, and memory. This can impact productivity, workplace performance, and road safety.
In teenagers and young adults, circadian rhythm disorders can cause risky behaviour, difficulty concentrating at school, controlling emotions, and coping with stress. Digestive disorders like stomach ulcers, gastroesophageal reflux disease (GERD), and irritable bowel syndrome can also arise due to circadian rhythm disorders. These disorders may influence the signalling from the brain to the gastrointestinal tract, leading to digestive symptoms.
Circadian rhythm disorders may also disrupt the hormone cycle that controls fertility and reproduction, leading to fertility problems. Metabolism disorders can also result from circadian rhythm disorders, which can lead to diabetes, metabolic syndrome, overweight, and obesity. Mood disorders such as irritability, anxiety, and depression can also be a result of circadian rhythm disorders. Lastly, circadian rhythm disorders can worsen other sleep disorders, such as sleep apnoea.
