Circadian Rhythm Sleep-Wake Disorders

By Admin

Do you ever feel that your life schedule keeps you from getting the rest you need? Or that waking in the morning is more difficult than it should be? You could have a circadian rhythm sleep-wake disorder. This class of disorders is characterized by irregular sleep-wake cycles that can readjust after a brief period or last for years. Like other sleep disorders, circadian rhythm disorders are often related to other conditions such as insomnia or sleep apnea, and treatment depends on the nature of the symptoms involved. Sleep-wake problems are often the result of life changes or routines that run counter to one’s natural endogenous rhythms. This can happen due to jet lag, a late shift at work, or a more serious medical condition that can threaten both your physical and mental health in the long term. With sleep disorders, every symptom can be a sign of circadian imbalance. Whether you’re adjusting to a recent change or have been dealing with irregular sleep times your entire life, your biological clock may be telling you something that should not be ignored.

Circadian Rhythms and Zeitgebers

There are currently about 60 million Americans with sleep problems, and many of these conditions are related to a lack of balance between biological needs and the modern-day environment. According to the National Institute of General Medical Sciences, circadian rhythm disorders develop when we try to sleep or wake at the wrong time, resulting in a desynchronization between internal sleep-wake rhythms and the environment. Patients can have insomnia, daytime sleepiness, or other problems as a result of body-clock misalignment. Over short durations these problems often correct themselves, but over longer periods of time they have the potential to cause serious harm. Persistent patterns of sleep/wake disturbance, whether from other disorders or from life patterns, can eventually create dysfunction within the biological clock system. Circadian rhythms are controlled by a region in the brain called the suprachiasmatic nucleus (SCN). This internal mechanism regulates body rhythms such as temperature, hormone levels, and the sleep-wake cycle. Situated within the hypothalamus, this master clock regulates brain and body functions in a 24-hour cycle that follows the light-dark cycle of the region. Cues known as zeitgebers (pronounced “zite-gebers”) keep us timed to our environments through daily experiences like weather, meals, medications, or exercise schedules. Since the SCN responds to zeitgebers, major changes such as a transition from day shifts to night shifts can have a variety of negative effects before a person is able to adjust. Also, as a person ages, the adjustment period tends to lengthen, making it more likely that sleep or health problems will develop as a result.

Types of Circadian Rhythm Sleep-Wake Disorders

Circadian rhythm sleep-wake disorders (CRSD) are organized into similar types in both the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and the International‌ ‌Classification‌ ‌of‌ ‌Sleep‌ ‌Disorders-3‌ ‌(ICSD-3)‌‌. Both of these manuals categorize the circadian rhythm disorders according to their causality, which ranges from internal to external, and from short-term to long-term durations.

Altered sleep phase types:

Altered sleep phase types of circadian rhythm disorders include both delayed and advanced sleep phase disorders, as well as the free-running type often referred to as non-24 hour sleep-wake disorder. These types are characterized by individual cycles that are out of sync with normal or expected wake times.

Delayed Sleep Phase Disorder (DSPD)

One of the most common sleep disorders, delayed sleep phase disorder, or delayed sleep phase syndrome (DSPS), is characterized by late sleeping and wakefulness. This disorder causes people to stay up late and sleep in, which can be a problem if these patterns do not coincide with life schedules. When attempting to force an earlier sleep schedule, people with delayed sleep problems can experience insomnia, excessive daytime sleepiness, and have an increased risk of depression and other emotional or mood problems. This disorder is common among teenagers (7-16 percent), usually around the age of early puberty when hormonal changes can alter sleep patterns.

Advanced Sleep Phase Disorder (ASPD)

Advanced sleep phase disorder, or advanced sleep phase syndrome (ASPS), is the opposite of delayed sleep phase disorder, causing people to fall asleep earlier and wake before the morning arrives. Some individuals with ASPD experience early morning insomnia or sleeping problems. While ASPD leads to less social conflicts than DSPD, it is still a common disorder with serious consequences in the long term. In contrast to DSPD, ASPD tends to be more common among the elderly, and is often associated with other disorders or comorbid health conditions.

Non-24-Hour Sleep-Wake Rhythm Disorder

Non-24-hour sleep-wake disorder, or non-24-hour sleep-wake syndrome, was termed “free-running type” in previous editions of the ICSD. Free-running sleep refers to sleep patterns that are not entrained to external cues. This can cause a number of problems as those with free-running sleep-wake rhythms tend to have circadian cycles that are longer than 24 hours and out of sync with the demands of daily life. In an attempt to adjust to these differences, a person’s internal clock may actually shift later each day as time goes on. This is very common among the blind, as their lack of direct light stimuli causes longer cycles. Brain trauma, other psychological issues, and comorbid conditions can also cause free-running misalignment symptoms.

Irregular Sleep-Wake Rhythm

Irregular sleep-wake rhythm refers to patterns that are completely detached from the light-dark cycles of day and night. Rather, an individual with irregular sleep-wake rhythms tends to sleep at randomized times and at varying lengths. Usually, this results in naps throughout both day and night. Much less common than other circadian rhythm disorders, irregular sleep-wake rhythms are more often associated with other medical or mental disorders, for example, dementia, brain trauma effects, or psychiatric conditions. By definition, those with irregular sleep-wake rhythms are experiencing fragmented sleep on a regular basis, which disrupts sleep architecture and fails to provide the body with enough sustained sleep time for normal staging.

External types:

Shift-Work Sleep Disorder

Anyone who has ever worked a night shift knows how it can affect sleep patterns. Regardless of the nature of the work involved, it takes some time to wind down from a shift and fall asleep. The later the work, the more likely the schedule with conflict with circadian rhythms, causing everything from delayed sleep onset and insomnia to anxiety dreams, excessive daytime sleepiness, and fatigue. Shift-work sleep disorder is usually the result of working hours outside of the traditional 9:00 to 5:00 standard, such as a night shift at a restaurant, or a security shift during late morning hours. Rotating work schedules are particularly susceptible, as it makes the routine more difficult to adapt to over time. While some individuals with later circadian preferences can adjust to later shifts, a rotating schedule can repeatedly disrupt the routine and make adjustment difficult for anyone. For those with comorbid medical, psychiatric, or other sleep disorders such as sleep apnea, these routines are particularly important, and their disruption can influence treatment outcomes. According to a study published in the journal Sleep Medicine Clinics, the dominating health problem reported by shift workers in America is disturbed sleep, with at least a quarter of the shift-working population experiencing sleep problems.

Jet Lag Disorder

Most people are familiar with jet lag due to long flights, and jet lag disorder simply refers to the conditions that can occur as a result. Jet lag develops when flying through more than one time zone, often new time zone, often during eastward travel, as the time difference demands earlier awakenings the further east one travels. Most often, this is a temporary condition that your brain and body adjusts to, but more extreme or repetitive experience with jet lag have the potential to cause longer-term symptoms.

Circadian Rhythm Disorders and Sleep Apnea

Sleep apnea, especially when untreated, can disrupt sleep architecture and cause a number of problems that can further impair sleep as well as daytime functions such as memory and cognition. And each apnea or hypopnea event can contribute to further disruptions as the body struggles to sleep through moments of shallow breathing, choking, or blockage in the upper airway. As a result, a considerable amount of overlap exists between sleep apnea and other sleep-related conditions. Among the most common forms of circadian rhythm disorders, shift-work disorder is by far the most prevalent among patients with sleep apnea. In studies of apnea symptoms among night shift workers, for example, there is significantly higher severity during daytime sleep, as opposed to night sleep. Researchers have concluded that changes in sleep-wake cycles can actually induce apnea events among those diagnosed with sleep apnea syndromes. As with other comorbid relationships, the shared symptoms of sleep apnea and circadian rhythm disorders allow for comprehensive treatments such as CPAP (continuous positive airway pressure) that can address multiple related disorder symptoms and improve overall sleep conditions.

Common Treatments

Since sleep problems are so often treated with self-medication habits such as drugs and alcohol, the American Academy of Sleep Medicine recommends a clean body and mind as a starting point for treatment. Keeping good sleep hygiene will avoid making the problems worse by masking them with temporary fixes. In addition, some use light therapy to help synchronize the body and mind with proper sleep-wake timing cues. Over the counter supplements like Melatonin have very promising success rates among some patients with circadian rhythm problems, but does not work for everyone. Prescribed medications such as hypnotics or mild sedatives may be required when symptoms are persistent or unmanageable. But lifestyle changes and/or behavioral therapy strategies will likely have the most long-term success in terms of overall health and wellbeing. Exercise, a healthy diet, proper sleep routines, and consistent nightly therapy will not only provide sleep-wake balance, but will improve memory and increase vitality, giving patients the chance to enjoy their time and feel better when they rise to face the day.