Actigraphy is an objective, unobtrusive measure of sleep at home, which can provide an important outcome measure in clinical practice.
Poor sleep is a common problem that is associated with a variety of illnesses, increased health care costs, and morbidity; in adolescents, poor sleep creates issues that negatively affect academic performance and may cause behavioral or psychological problems. A number of different studies have shown that there is a high prevalence of sleep disorders among adolescents. These are often cited as being due to psychological or hormonal factors, as well as inadequate sleep habits. A number of factors are related to the high prevalence of sleep disorders among adolescents, giving rise to their being very tired and drowsy during the day. The interruption of their normal sleep habits at the weekend and an insufficient number of hours of sleep during the week are related to the appearance of insomnia. Adolescents experience nonrestorative sleep (NRS) due to their school schedules, which is a frequent symptom that is often associated with mental disorders and characteristics of sleep deprivation (such as extra sleep time on weekends). NRS can cause greater daytime impairment than difficulty initiating or maintaining sleep in adolescents; thus insomnia is not an issue. Some data suggest that pubertal development may be involved in the sleep rates or troubles observed in adolescents, and results also show that persistent sleep disorders are significantly associated with physical, psychological, or social difficulties. It is essential to take an interest in the quality of sleep in adolescents, which may be a way to approach their psychosocial difficulties. Complementary studies should be undertaken to describe the daytime repercussions of insomnia for this specific age group of the general population and to measure these repercussions. Using more delineated criteria to assess poor sleep increases the recognition of adolescents who complain about sleep. Classifications should be developed and engaged to improve the correct identification of problems in adolescents related to poor sleep, and sleep-deprived adolescents should also not be neglected. Unfortunately, polysomnography may not be practical to properly assess and diagnose conditions that cause poor sleep in adolescents so sleep diaries and actigraphy offer alternatives.
Keeping a Sleep Diary
Sleep diaries provide a daily record of an individuals sleep habits, such as bed and wake times, and are widely used in research and clinical settings. Actigraphy measures body movements and provides an objective estimate of sleep. It is not as widely used as sleep diaries or polysomnography, but may be particularly useful in research with adolescents. It has been suggested that sleep diaries and actigraphy may complement each other by providing subjective and objective data, respectively. While actigraphy has been used in research studies for many years, until recently, methodological issues had not been systematically addressed in clinical research and practice. The issues have now been addressed, and actigraphy may be reaching the maturity needed for application in the clinical arena.1 The American Sleep Disorders Association determined actigraphy to be a useful adjunct tool in the study and clinical assessment of sleep disorders, providing information obtainable in no other practical way. It can also have a role in the medical care of patients with sleep disorders; however, it should not be held to the same expectations as polysomnography. Actigraphy is one-dimensional, whereas polysomnography comprises at least three distinct types of data (EEG, EOG, and EMG) that jointly determine whether a person is asleep or awake. Although actigraphy is not appropriate for the diagnosis of sleep disorders, more recent studies suggest that for some disorders, particularly those associated with poor sleep in adolescents, actigraphy may be more practical than polysomnography.
A recent independent review of the clinical applicability of actigraphy by Acebo et al2 found that there was no relationship between sleep measures and health-related symptoms. Their interpretation of the data is not conclusive, and there is a need to determine whether actigraphy is reliable enough to establish the relationship between sleep changes and quality of life measures in adolescents.
The one area where actigraphy has been definitively established for clinical diagnosis is in the evaluation of circadian rhythm disorders. Actigraphy has been shown to be very good for identifying rhythms, and results of recordings from actigraphy correlate well with measurements of melatonin and of core body temperature rhythms. In adolescents in 9th and 10th grades where school start time was 8:25 am and 7:20 am, respectively, assessments were performed to identify whether early start times were associated with sleep deprivation, quality of life measures that directly impact academic performance and psychosocial well-being. Assessments included 2 weeks of actigraphy and sleep diaries at home, followed by a 22-hour laboratory evaluation, including evening saliva samples every 30 minutes in dim light for determination of dim-light salivary melatonin onset phase, overnight sleep monitoring, and the multiple sleep latency test (MSLT). Researchers found that early start time was associated with significant sleep deprivation and daytime sleepiness. In addition, the occurrence of REM sleep on the MSLT indicated that clinicians should exercise caution in interpreting MSLT REM sleep in adolescents evaluated on their usual schedules. The conclusions noted by the authors were that psychosocial influences and changes in bioregulatory systems controlling sleep could limit teenagers capacities to make adequate adjustments to an early school schedule.3
Another groups high school children were evaluated where researchers found that total sleep times and wake times were longer and later than estimated with actigraphy and reported on diaries. Moreover, school and weekend night survey variables were significantly correlated with both diary and actigraphy variables. Strengths of the associations were consistently greater for school night variables than the corresponding weekend night variables, and the findings support the validity of the Sleep Habits Survey estimates in comparison with diary and actigraphy.4 Actigraphy may be used for behavioral analysis including individual regulation of motor activity as an objective parameter to evaluate psychiatric disorders and has been effectively used to confirm damped circadian rhythms in adolescents with mild depressive disorders and highlight the influence of gender and age on these measures.5,6 Actigraphy has been effective in determining the negative effects of work on adolescents who for socioeconomic reasons must attend school and contribute income to their households.7 The AASM also recommends actigraphy in characterizing and monitoring circadian rhythm patterns or disturbances in adolescents.8
Measurements to Consider
Sleep is often assessed in circadian rhythm studies, and long-term monitoring is required to detect any changes in sleep over time9; however, it has been shown that 5 or more nights of usable recordings are required to obtain reliable actigraphy measures of sleep for adolescents, and reliability estimates for values aggregated over any 5 nights are adequate for sleep start time, wake minutes, and sleep efficiency.2 Measures of sleep minutes and sleep period are less reliable and may require 7 or more nights for estimates of stable, individual differences while reliability for 1- or 2-night aggregates is poor for all measures. In a group of adolescents on an atypical schedule of 18-hour nights, marked differences in sleep as function of prior sleep deprivation were noted, and extended sleep beginning about 4 hours in advance of entrained sleep onset phase was not associated with a return of slow-wave sleep (SWS). Activity records show sleep disturbance when sleep is attempted at an unfavorable phase of the circadian cycle, so actigraphy can aid in the diagnosis of delayed or advanced sleep phase syndrome, and non-24-hour-sleep syndrome, and in the evaluation of sleep disturbances in shift workers.10 It must be remembered, however, that those overt rest-activity rhythms are susceptible to various masking effects, so they may not always show the underlying rhythm of the circadian pacemaker. Actigraphy also works well in sleep space both as a way of detecting bedtimes and wake times and as a representation of sleep restlessness.11 Actigraphy is still not appropriate for the diagnosis of SDB or of periodic limb movements in sleep; however, it is highly appropriate for examining the sleep night-to-night variability for adolescents with insomnia. Actigraphy is also appropriate for the assessment and stability of treatment effects of anything from hypnotic drugs to light treatment to CPAP, particularly if assessments are done before and after the start of treatment.
Although actigraphy is not as accurate as polysomnography for determining and diagnosing SDB and some sleep measurements, studies are in general agreement that actigraphy is appropriate in the assessment of poor sleep in adolescents and as an effective measurement of treatment effectiveness. Actigraphy has the ability to record continuously for long time periods, is more reliable than sleep logs that rely on patients recall of how many times they woke up or how long they slept during the night, and is more reliable than observations that capture only short time periods. Patients perception of their sleep provides less detail and accuracy than actigraphy; the actigraph is an objective, unobtrusive measure of sleep at home in adolescents and can provide an important outcome measure in clinical practice. It is doubtful whether actigraphy data will ever be equivalent to polysomnography, although progress on hardware and data processing software is continuously being made. Actigraphy is reliable for evaluating sleep patterns in patients with insomnia and for studying the effect of treatments designed to treat insomnia, and provides a reliable tool for use in the clinical setting to assess sleep disorders in adolescents.
Vernon R. Pertelle, MBA, RRT, CCM, is corporate director of respiratory/HME services for Apria Healthcare, Lake Forest, Calif. He can be reached via e-mail at [email protected].
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