As infants, persons with SMS are generally described by their parents as happy, easy going babies who are complacent, sometimes lethargic, and often sleeping more than might be expected (Smith and Gropman, 2000). The sleep disturbance may go unrecognized in infancy. However, new evidence suggests that the sleep disturbance begins as early as one year of age and continues into adulthood. Children with SMS demonstrate shortened sleep cycles for their age, with frequent awakenings (arousals) during the night, early sleep offset (5:30-6:30 AM) and increased daytime sleepiness (napping) during daylight hours. The sleep disturbance in SMS is chronic, occurring almost every night, thereby impacting the child's daytime behaviors, as well as family and school life.
Efforts to understand sleep patterns and habits in SMS individuals have led to the confirmation of an unusual inverted circadian rhythm of melatonin. Melatonin is a hormone secreted by the pineal gland that helps control body rhythms and sleep wake cycles in relation to daylight. The timing of melatonin release is controlled by the internal circadian “clock” that is located in a part of the brain called the suprachiasmatic nucleus, or SCN. Throughout the plant and animal kingdom, melatonin levels rise in the evening, peak during the night, and then fall to very low values during the day. In addition, light that enters the eye at night suppresses the nocturnal rise of melatonin. Based on research conducted by Dr. Lorraine Potocki at Baylor College of Medicine (Potocki et. al., 1997; 2000) and confirmed later in France by Dr. Helene DeLeersnyder (DeLeersnyder et. al., 2001), this normal rhythm or cycle of melatonin does not appear to be the case in persons with SMS. Future research to understand this conundrum must answer two critical questions: (1) why is the circadian rhythm of melatonin inverted? and (2) why doesn't light suppress melatonin levels like it does in other species?
The therapeutic management of the sleep disorder in SMS remains a challenge for physicians and parents. There are no published well-controlled treatment trials. Melatonin dispensed over-the-counter is not regulated in the U.S. by the FDA; thus, dosages may not be exact. No formal melatonin treatment trials have been conducted. Early reports of therapeutic benefits from melatonin remain encouraging. Some parent report that melatonin taken at bedtime have been provides general improvement of sleep without reports of major adverse reactions. A monitored trial of four to six weeks on low-dose (3 mg) melatonin may be worth considering in affected individuals with major sleep disturbance. Consultation with a sleep specialist or your pediatrician is recommended before using doses above 3 mg. Doses above 5 mg taken in the evening can remain in the body into the next day and produce sleepiness and decreased alertness.
Other families have had limited success with different sleep medications other than melatonin. Finally, some families with young children have tried an enclosed bed system with much success. In regards to enclosed beds, please note that one of the manufacturers, Vail Products, Inc. (Vail Beds), is permanently ceasing the manufacture, sale and distribution of all Vail enclosed bed systems.
Sleep histories are important for documenting developmental changes in sleep/wake schedules and respiratory function. A sleep diary (a detailed hourly record of an individual's actual sleep-wake pattern for a week or more) may prove helpful in documenting sleep/wake schedules. Evidence of sleep-disordered breathing warrants polysomnogram and overnight sleep study to evaluate for obstructive sleep apnea. For help finding a sleep clinic in your area, check out the American Academy of Sleep Medicine.
In September 2002, the SMS Research Unit at the National Institutes of Health began a Home Assessment of Sleep (SMS-HAS). As described below, this study includes several non-invasive measures to study the sleep-wake cycle in SMS in the home setting.
Parents chart their child's sleep/wake patterns using a standard monthly sleep diary. The form permits the primary caretaker/parent to note times when their child is sleeping/napping or awake. At the end of each month, the competed diary is returned to the SMS Research Unit, where it is scanned and transferred into a digital format. Dr. Wallace Duncan, a sleep and circadian biologist at the NIH, uses statistical analysis and special research software to calculate the average amount of sleep and awake times for the month. By collecting sleep diaries for several consecutive months, a quantitative picture of a child's sleep pattern emerges. This information can then be related to different drug or school schedules.
Any families interested in charting their child's sleep are welcome to a copy of the Monthly Sleep Diary form. Families considering a new medication trial may find the sleep log useful to monitor how the medication impacts their child's sleep. When a new medication trial is considered, keeping the sleep log for the 1-2 weeks prior to using the new medication and then continuing to track sleep patterns over the course of the trial, may be useful in monitoring medication impact on sleep patterns. Noting the medication dosage and time given are critical to understanding drug effects.
For more information on current research see the Current SMS Research page.
Home Assessment of Mood & Behavior
In conjunction with the sleep diary, the primary caretaker is also asked to rate their child's mood/behavior twice daily, using a simple visual line scale.
Wrist Activity Monitor Actiwatch
Another tool used for the SMS-HAS is the wrist activity monitor, or Actiwatch. This monitor is a small wristwatch like device used to record the child's movements. Worn on the child's non-dominant wrist, the Actiwatch objectively measures activity and rest patterns during each 24-hour day. Individuals with SMS are asked to wear the activity monitor for up to 2 months or longer as tolerated. Inside the watch is a microchip that records the activity. When the watch is returned to NIH, Dr. Duncan downloads the critical rest/activity data to create an activity/rest profile.