Link to original: http://sphynxcatvp.nocturna.org/health/sc-irregularsleep.html
Patients with Irregular Sleep-Wake Pattern will usually have a typical average sleep time within a 24 hour period, but it will be broken up into three or more shorter blocks of sleep time in each 24hr time period. This article will go into the differences between this and other circadian rhythm disorders.
What is irregular sleep-wake disorder?
Unlike patients with Advanced Sleep Phase, Delayed Sleep Phase, and Non-24 Sleep-Wake Syndrome, a sleep log kept by patients will show no recognizable patterns of sleep or wake times. Instead, sleep will be broken up into multiple shorter blocks in each 24-hr time period, with great unpredictability in sleep-wake timing.
What are the symptoms?
Page 127 of the ICSD 2001 states:
- The patient has a complaint of either insomnia or excessive sleepiness.
- The patient has an irregular pattern of at least three sleep episodes during a 24-hour period.
- The sleep pattern has been present for at least three months.
- Total average sleep time per 24-hour period is normal for age.
- Disturbed chronobiologic rhythmicity is demonstrated by either of the following:
- Continuous polysomnographic monitoring for at least 24 hours shows a loss of the normal sleep-wake pattern
- Continuous temperature monitoring for at least 24 hours shows a loss of the normal temperature
- No medical or mental disorder accounts for the symptom.
- The symptoms do not meet the criteria for any other sleep disorder causing insomnia or excessive sleepiness.
- Minimal Criteria: A plus B plus C, OR, B plus E.
Severity is graded on the respective amount of insomnia or excessive sleepiness; higher severity with more insomnia/sleepiness.
How is it diagnosed?
As with any really unusual medical condition, the hardest part is often getting a doctor to take you seriously in the first place!
Generally the patient will be first advised to maintain a log of their wake/sleep times. This will be the fastest way to see what your sleep patterns are like, see if you're getting a decent sleep in any sleep interval, and if any predisposing factors are at work.
Predisposing factors include: work schedule, pain levels, depression, excessive time spent in bed (voluntarily or involuntarily), anemia (which can leave a patient tired all the time if it progresses far enough), sleep apnea, restless limbs during sleep, and so on. While most cases of Irregular Sleep-Wake tend to be due to a brain dysfunction, it's important to rule out any treatable or simple cause first!
A sleep study up to three days in length may be required (to monitor all wake/sleep periods) if there is a need to rule out other sleep disorders - this can be done in a lab, or at home with a small device usually worn on the wrist called an "Actigraph".
Brain imaging tests may show the presence of a physical brain abnormality that is contributing to the sleep problem.
How is it treated?
Treatment for irregular sleep-wake rhythm is aimed at trying to increase stimulation to reset the sleep clock in the brain. The goal is to have one long sleep time at night and one long awake time during the day.
Bright light therapy
This works by increasing the amount of natural sun exposure - or it's equivalent - during the day, and avoiding it during the evening and night. Specially designed "daylight bulbs" may be more useful to some if sun exposure isn't practical. These daylight bulbs can be acquired in various forms, such as a light box, a desk lamp, and even a visor that you wear.
Improving sleep hygiene
Various sleep hygiene improvements will be suggested such as maintaining a regular sleep schedule - even on weekends, encouraging evening activities that will help the patient stay awake until the desired sleep time, and making the sleep environment more comfortable.
Melatonin, sleep aids, wake aids, vitamin B12, and other medications and supplements may be used in an attempt to reset the sleep clock and keep it that way. Physical activity is encouraged duirng the day, and minimal noise and activity at night.
- American Sleep Association: Irregular Sleep-Wake Rhythm
- Ann Acad Med Singapore 2008 Aug;37(8):669-76: Treatment....with Light (PDF)
- PubMed: The Impact of Short, Irregular Sleep Opportunities
- Sleep. 2007 November: Circadian Rhythm Sleep Disorders: Part II (PDF)
- Sleep Med Clin. 2009 June: Circadian Rhythm Sleep Disorder (PDF)
- Sleep Medicine Clinics 2009 Feb: Circadian Rhythm Sleep Disorder: ISWR(PDF)
- UM Medical Center: Irregular Sleep-Wake Syndrome Overview