As of 2005, circadian rhythm sleep disorders are classified as neurological disorders. In layman’s terms, a circadian rhythm sleep disorder is one that results from a disrupted circadian rhythm. In such a disruption, a person’s circadian (or biological) clock is out of sync with a 24-hour day.
Circadian is a Latin word that basically means “around the day”. The circadian rhythm (a.k.a. body clock) regulates certain biological processes around a 24-hour time frame. Studies have shown that human beings are naturally predisposed to a slightly longer ‘day’, usually consisting of 24 hours and a few minutes. Instead of adding a few minutes to every day, the calendar dictates that every four years, we simply add a catch-up day – i.e. a leap year.
Unfortunately, this system doesn’t work for human beings who have to function daily within a 24-hour time frame. What helps us to do so is our body clock. It basically synchronizes our natural ‘24 hour plus’ instincts to fit into a 24-hour cycle. Sleep-wake times are one of the key processes controlled by circadian rhythms. Other processes include core body temperature, hormone secretions, hunger cues and cell regeneration. These processes generally occur at the same times each day, provided our circadian rhythms are on task. When they’re not, any number of functions can be slightly out of whack. Most notably for this article, the function of sleep.
A disrupted circadian rhythm can cause sleep disorders that range from mild to disabling. They can be counteractive to leading a normal work and personal life. In addition, a disruption of the body clock can cause or compound other physical and psychological health problems including cardiovascular, metabolic, cognitive and mood disorders, as well as depression. They can also make it unsafe for us to drive, operate machinery or perform many daily functions. Disruptions of the circadian rhythm can be caused by extrinsic (outer) or intrinsic (inner) factors. Some are caused, or exacerbated, by a combination of both.
There are 5 (formerly 6) different types of circadian rhythm sleep disorders, each with their own symptoms and problems.
DSPD is common in pre-teens, teens, and young adults. A person with DSPD might be regarded as a ‘night owl’ but DSPD is more extreme than that. In the case of delayed sleep phase disorder, sleep onset is usually 2 am or later. DSPD sufferers are most awake and alert in the middle of the night. It’s possible for DSPD sufferers to obtain a full night’s rest, but only if they’re permitted to sleep an age-appropriate duration following onset.
DSPD becomes problematic when, in the daily lives of these young people, school and work schedules aren’t adaptable to DSPD. This can result in chronic oversleeping and promote excessive tiredness and difficulty performing required tasks. School work, social relationships, part time jobs and after school activities can be affected. Studies show that delayed sleep phase disorder may have genetic causes – a biological propensity toward being nocturnal. DSPD can also be caused, or aggravated, by physiological, behavioral and environmental factors.
ASPD might be thought of as the opposite of DSPD. Coincidentally, it tends to most commonly affect the elderly. People with ASPD also sleep outside of ‘normal’ time frames. In this case, the onset of sleep is advanced several hours, often to as early as 6 pm. People with ASPD might wake for the day as early as 1 am. Similar to DSPD, those who have ASPD can obtain a ‘normal’ night’s sleep of good quality, provided that their daily schedule accommodates it. Since it primarily affects older people, it may be easier to adjust a lifestyle around ASPD than DSPD. Even those with jobs can usually meet work scheduling obligations, particularly if allowed flexibility to arrive at and leave work early.
When ASP sufferers don’t have schedules that accommodate their sleep patterns, problems arise that affect work, socialization, safety, and health. ASP is also similar to DSP in that it can have both biological and environmental causes.
Shift work disorder is particular to those who work rotating shifts or ‘odd hours’ such as overnight or from early in the morning. In this case, work schedule(s) and/or frequent changes in work schedules are at constant odds with a person’s circadian rhythms. Quite a bit of research is being done in regard to shift work disorder, as so many industries and job types require that work shifts are filled at any or all times of the day and night.
Not all irregular and night shift workers have shift work disorder. In fact, a surprising majority don’t, as their internal clocks allow them to adjust to these variations. Most are able to obtain a satisfactory amount of sleep (7-8 hours undisrupted) when not at work. For those whose internal clocks can’t adjust, those whose outside of work schedules won’t allow time for this ‘full night’s rest’ or those with other sleep or health issues, shift work disorder can result in chronic sleep deprivation and promote serious problems.
Irregular sleep-wake disorder can occur when, as a result of neurodegeneration or injury, circadian sleep-wake rhythms become disorganized. Dementia, mental retardation, and brain tumors are also risk factors for ISWD. ISWD sufferers tend to sleep in short, irregularly spaced ‘naps’ throughout a 24-hour period. In addition to neurological causes, ISWD is also the circadian rhythm sleep disorder most commonly associated with institutional living. This is due to decreased exposure to natural light & dark, a lack of structured activities, night time noise, side effects from medicine and sleep-disruptive medication schedule adherence.
People who have ISWD will be excessively tired as well as in a state of chronic insomnia. Where a lack of neurologic or other biological causes are present, an institutionalized patient can re-adjust to normal sleep patterns when they’re no longer living in these circumstances.
In the absence of any biological or compounding environmental factors, jet lag disorder is temporary and found throughout the general population. It occurs as a result of traveling between time zones. The more time zones crossed, the more impactive jet lag can feel. Traveling east is a more difficult zone adjustment than traveling west, as it’s easier to adapt to delayed sleep than to advanced sleep. Traveling west presents the problem of staying asleep during the adjusted time frame, though. Jet lag causes sluggishness and tiredness. It can also trigger appetite changes, digestive irregularities, and moodiness.
Usually, within a few days, those who have normally functioning circadian rhythms or ‘body clocks’ will adjust to a time zone change. Thus, it’s no longer classified as a circadian rhythm sleep disorder. It can become problematic, though, when a person travels between time zones frequently, without sufficient time to adjust and maintain sleep schedules in between.
Common among the visually impaired, the brains of Non-24 sleep disorder sufferers can’t detect light cues that signal circadian rhythms. Sleep patterns and peak alertness times are variable and irregular. Approximately half of all blind people suffer from Non-24. Constantly progressing through a 24 hour ‘plus’ day, Non-24 sleep hours are always being pushed forward. As this is a continual progression, people with Non-24 will, at times, be in cycles where they’re sleeping during ‘normal’ hours. They’ll then progress out of it again, and so on. Over time, Non-24 becomes entrenched and severe, and quite disabling.
Non-24 Sleep-Wake Disorder also occurs, rarely, in sighted people. In these cases, causes can vary and haven’t all been identified. People with dementia or developmental disabilities can suffer from Non-24 Sleep-Wake Disorder.
Circadian rhythm sleep disorders can have many different causes, both biological (such as unusually short or long circadian rhythm cycles) or environmental (such as frequently changing or ‘odd’ schedules or overstimulation, such as in an institution). Often, there is a combination of both.
Many CRSD treatments are similar but will be utilized differently based on the type of disorder and the schedule that one needs to maintain.
Although total recovery from a sleep disorder is often unattainable due to the variety of causes and other factors involved, in many cases, improved sleep schedule and quality, as well as improved daily functioning and health, is a possibility. The primary goal, in treating circadian rhythm sleep disorders, is to help a patient be functional within the demands of his or her lifestyle.
In most cases, there’s really no way to prevent a circadian rhythm sleep disorder, as most of them are, at least in part, caused by biological factors. However, there are some basic strategies that everyone can use to try to promote as much restful sleep as possible.