Circadian Rhythm Sleep Disorder

Your body has a natural clock that tells you when to sleep and wake, but when this clock falls out of sync with the world around you, it can affect your daily life in serious ways.

Table of contents

• What are circadian rhythm sleep disorders?
• Types of circadian rhythm disorders
• Symptoms
• What causes these disorders?
• How are they diagnosed?
• Treatment options
• Prevention and living with the condition

What are circadian rhythm sleep disorders?

Circadian rhythm sleep disorders are conditions that happen when your body’s internal clock doesn’t match up with your environment^[1]. The word “circadian” comes from Latin and means “around the day”^[1]. This internal clock, called the circadian rhythm, runs on roughly 24-hour cycles and controls when you feel sleepy and when you feel awake^[2].

These disorders are also known as circadian rhythm sleep-wake disorders or sleep-wake cycle disorders^[1][2]. The problems occur when your body’s clock becomes out of sync with cues from your environment, like when it gets light or dark outside, when you eat, and when you are physically active^[2].

Inside your brain is a structure called the hypothalamus, which contains small control centers known as the suprachiasmatic nuclei (SCN)^[5]. These nuclei work together with other parts of the brain to regulate your circadian rhythms and control various body functions^[5]. Light plays the largest role in setting your circadian clock, as a pathway runs from your eyes to the SCN^[5].

Most circadian rhythm disorders are rare, affecting about 3% of people worldwide^[1]. However, some forms like jet lag and shift work sleep disorder are much more common^[1].

Types of circadian rhythm disorders

There are several different types of circadian rhythm disorders, each affecting sleep timing in distinct ways^[1]:

Jet lag disorder happens when you travel quickly across multiple time zones, taking you out of sync with the day and night schedule you’re used to^[1]. Jet lag is common and expected for travelers flying to a destination with at least a two-hour time difference^[1].

Shift work sleep disorder (SWSD) occurs when you have trouble adjusting your circadian rhythm to your work schedule^[1]. This affects about one-third of people who work shifts during nighttime hours^[1]. The severity varies depending on how often shifts change, whether they make sleep and wake times earlier or later, and how long the shift lasts^[4].

Delayed sleep-wake phase disorder (DSWPD) means your sleep and wake schedule is much later than the average person^[1]. The normal sleep interval is pushed back two or three hours, so you don’t feel tired until after midnight and prefer to sleep until mid-morning^[13]. This is more common in children, teenagers, and young adults^[1][4]. People with this disorder cannot fall asleep earlier even if they try^[4].

Advanced sleep-wake phase disorder (ASWPD) is when you go to bed earlier and wake earlier than the average person^[1]. The normal sleep interval is moved up two or three hours, so you prefer to fall asleep in the very early evening and wake up in the early morning hours^[13]. This is more common among older adults^[1][4]. People with this disorder cannot stay awake until later times even if they try^[4].

Irregular sleep-wake rhythm disorder (ISWRD) causes sleep and wake times to happen at unpredictable, disorganized intervals^[1]. Sleep intervals are short, perhaps two to three hours long, and spread throughout the day^[13]. This usually happens to people with dementia or other degenerative brain diseases^[1][13].

Non-24-hour sleep-wake rhythm disorder (N24SWD) occurs when your circadian rhythm is predictable but isn’t 24 hours like most people’s^[1]. The normal daily circadian clock is extended two or three hours^[13]. Instead of wanting to sleep every 24 hours, you may not be ready to sleep until 25 or 26 hours after your previous sleep onset, causing sleep and wake times to change daily^[13]. This syndrome is much less common and tends to occur in blind people who cannot perceive light^[4][13].

Symptoms

The symptoms of circadian rhythm disorders revolve around sleep and waking, and they vary depending on the particular disorder^[1]. Because people cannot sleep when they need to, they may be sleepy during the day and have difficulty concentrating, thinking clearly, and doing their usual activities^[4].

Common symptoms include^[1]:

• Trouble falling asleep (insomnia)
• Difficulty staying asleep
• Trouble falling back asleep during the middle of the night or early in the morning
• Waking up earlier than you want or plan
• Trouble waking up (sleep inertia) or unpredictable sleep-wake times
• Sleepiness during the day, which can lead to hypersomnia (excessive sleepiness)
• Needing to nap during the daytime
• Fatigue
• Headaches
• Depression, irritability, and other issues due to lack of sleep

You may have symptoms such as extreme daytime sleepiness, decreased alertness, and problems with memory and decision-making^[2]. People with these disorders often have an irregular circadian rhythm that can have a negative effect on their ability to sleep and function properly, and can result in mood disorders such as depression, anxiety, and seasonal affective disorder^[19].

What causes these disorders?

Causes of circadian rhythm sleep disorders can be internal or external^[4]. People with circadian rhythm disorders often have differences in their body’s natural clock or related processes^[1].

Internal causes include^[4]:

• Damage to the brain—for example, due to a brain infection (encephalitis), stroke, head injury, or Alzheimer disease
• Insensitivity to the cycle of night and day

External causes include^[4]:

• Jet lag, especially when traveling from west to east
• Working irregular shifts on a regular basis
• Frequently going to bed and getting up at different times
• Being confined to bed for a long time
• Blindness or not being exposed to sunlight for long periods of time
• Taking certain medications or illicit drugs

Sleep-wake reversals are common among people who are hospitalized because they are often awakened during the night and because their eyes are not exposed to sunlight long enough during the day^[4].

Your circadian rhythm is controlled by genes that help regulate light-induced adjustments. These include positive regulators BMAL1 and CLOCK and negative regulators PER1 and CRY^[5]. All of us are born genetically with a predisposition to a very specific chronotype, meaning the time of day when we prefer to be asleep and when we’re most cognitively alert^[17]. Anyone who’s on the far end of the spectrum—early birds or night owls—or doesn’t align with the spectrum at all could be at risk for a circadian rhythm sleep disorder^[17].

How are they diagnosed?

To diagnose a circadian rhythm disorder, your doctor may ask about your sleep habits and may suggest a sleep study and some other diagnostic tests^[2]. Your sleep specialist will begin by asking questions about your sleep preferences and family history, since circadian rhythm disorders can run in families^[13].

To learn more about your habits, they may recommend that you keep a sleep log for several weeks^[13]. You may also be asked to wear an actigraphy monitor, a watch-like device that records activity, light exposure, sleep, and wake times^[13].

Treatment options

Your treatment plan will depend on the type and cause of your circadian rhythm disorder^[2]. Treatments for circadian rhythm disorders aim to reset your sleep-wake rhythm to align with your environment^[8]. The most common treatments are healthy lifestyle changes, bright light therapy, and melatonin^[8]. Often, your doctor will recommend a combination of these treatments^[8].

Most of these disorders are treatable, and some are temporary and resolve with simple changes or adjustments^[1]. Therapy for circadian rhythm disturbances is largely behavioral^[12].

Healthy lifestyle changes

To help reset your sleep-wake cycle, your doctor may recommend that you establish a daily routine with set activities that happen during the day and another set of activities that happen at night^[8]. These practices include^[8]:

• Keep a regular meal schedule, especially if you are a shift worker or sleep at irregular times of the day or night
• Start a regular bedtime routine. Sleep in a cool, quiet place and follow a relaxing bedtime routine that limits stress
• Avoid daytime naps, especially in the afternoon. However, shift workers may benefit from a short nap before the start of their shift
• Get regular physical activity during the daytime and avoid exercising close to bedtime
• Limit caffeine, alcohol, nicotine, and some medicines, especially close to bedtime
• Manage your exposure to light

Enhancing environmental cues is an important part of treatment. Patients are encouraged to keep a dark, quiet room during sleep and a well-lit room upon awakening^[12]. Bright light exposure in the evening should be avoided, and regular hours of eating and other activities should be enforced^[12].

Chronotherapy

The hallmark treatment for circadian rhythm disorders uses light therapy and/or melatonin—a natural hormone your body makes to help induce sleep—to affect the body’s natural circadian rhythm^[13]. You may need just one or both and may need to use them periodically or for life^[13].

Bright light therapy: Exposure to bright lights tells your brain that it should be awake^[13]. Light therapy has been shown to be an effective modifier of circadian cycles^[12]. For adjustment purposes, bright room light over time may be sufficient; however, a higher intensity of light (greater than 6000 lux over 30 to 60 minutes) is often necessary to accomplish acute phase shifts^[12].

The timing of light therapy is important because it affects the degree and direction of the rhythm shift^[12]. Light therapy applied in the early evening and nighttime hours delays the cycle, whereas therapy given in the early morning stimulates morning alertness and an earlier bedtime^[12]. Your doctor will specify when and for how long to use bright light therapy^[13].

Melatonin therapy: Taking melatonin at specific times helps your body recognize when it should be sleeping. Your doctor will specify when and how much melatonin to take^[13]. Light seems to play the largest role in setting your circadian clock, and sunlight and other time cues are used to keep your clock set from day to day^[5].

This behavioral treatment consists of a gradual shift in sleep time in accordance with the patient’s tendency^[12]. In delayed sleep-phase syndrome, a progressive delay of 3 hours per day is prescribed, followed by strict maintenance of a regular bedtime hour once the desired schedule is achieved^[12]. In advanced sleep-phase syndrome, treatment focuses on advancing bedtime by 2 to 3 hours per night over 1 week until a desired schedule is achieved^[12].

Medications

Tasimelteon is approved for treatment of non-24-hour sleep-wake disorder in the totally blind^[12]. Study results demonstrated that tasimelteon adjusts the master clock (both melatonin and cortisol) and has clinically meaningful effects on the sleep-wake cycle in terms of the timing and amount of sleep^[12].

Prevention and living with the condition

You can take steps to prevent circadian rhythm disorders by making healthy lifestyle changes to improve your sleep habits^[2]. If left untreated, circadian rhythm disorders may increase the risk of certain health problems or lead to workplace and road accidents^[2].

Sleep is more important now than ever. Getting enough sleep and maintaining a regular schedule for optimal circadian rhythm health is a challenge for most of us^[16]. Sleep does more than just make us feel better the next day—it allows us to pay close attention, remember new information, and multitask^[16]. Regularity of sleep and wake also maintains the health and optimal function of the circadian timing system^[16].

Insufficient sleep and irregular sleep-wake schedules can impair our health, weaken our immune system, increase inflammation, and even lead to increased vulnerability to viral illnesses^[16].

Tips for optimal sleep and circadian rhythm health include^[16]:

• Use extra time for sleep to pay off any sleep debt you may have accumulated
• Keep the same sleep schedule 7 days a week
• Set your alarm for the same time each morning. A consistent wake time is key to maintaining a structured routine for the rest of your day
• Get bright light exposure during the day, especially in the first hour or two after waking. Our body clocks are set by morning bright light exposure, particularly when received around the same time every day

Disruptions in your sleep patterns can be temporary and caused by your sleep habits, job, or travel. Or a circadian rhythm disorder can be long-term and caused by aging, your genes, or a medical condition^[2]. Working from home may allow you the time and flexibility to keep the same sleep schedule 7 days a week^[16].