In summary, although actigraphy is not as accurate as PSG for determining some sleep measurements, studies are in general agreement that actigraphy, with its ability to record continuously for long time periods, is more reliable than sleep logs which rely on the patients' recall of how many times they woke up or how long they slept during the night and is more reliable than observations which only capture short time periods Actigraphy can provide 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 3 distinct types of data (EEG, EOG, EMG), which jointly determine whether a person is asleep or awake It is therefore doubtful whether actigraphic data will ever be informationally equivalent to the PSG, although progress on hardware and data processing software is continuously being made Although the 1995 practice parameters paper determined that actigraphy was not appropriate for the diagnosis of sleep disorders, more recent studies suggest that for some disorders, actigraphy may be more practical than PSG While actigraphy is still not appropriate for the diagnosis of sleep disordered breathing or of periodic limb movements in sleep, it is highly appropriate for examining the sleep variability (ie, night-to-night variability) in patients with insomnia Actigraphy is also appropriate for the assessment of 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 A recent independent review of the actigraphy literature by Sadeh and Acebo reached many of these same conclusions Some of the research studies failed to find relationships between sleep measures and health-related symptoms The interpretation of these data is also not clear-cut Is it that the actigraph is not reliable enough to the access the relationship between sleep changes and quality of life measures, or, is it that, in fact, there is no relationship between sleep in that population and quality of life measures? Other studies of sleep disordered breathing, where actigraphy was not used and was not an outcome measure also failed to find any relationship with quality of life Is it then the actigraph that is not reliable or that the associations just do not exist? The one area where actigraphy can be used for clinical diagnosis is in the evaluation of circadian rhythm disorders Actigraphy has been shown to be very good for identifying rhythms Results of actigraphic recordings correlate well with measurements of melatonin and of core body temperature rhythms Activity records also show sleep disturbance when sleep is attempted at an unfavorable phase of the circadian cycle Actigraphy therefore would be particularly good for aiding in the diagnosis of delayed or advanced sleep phase syndrome, non-24-hour-sleep syndrome and in the evaluation of sleep disturbances in shift workers It must be remembered, however, that overt rest-activity rhythms are susceptible to various masking effects, so they may not always show the underlying rhythm of the endogenous circadian pacemaker In conclusion, the latest set of research articles suggest that in the clinical setting, actigraphy is reliable for evaluating sleep patterns in patients with insomnia, for studying the effect of treatments designed to improve sleep, in the diagnosis of circadian rhythm disorders (including shift work), and in evaluating sleep in individuals who are less likely to tolerate PSG, such as infants and demented elderly While actigraphy has been used in research studies for many years, up to now, methodological issues had not been systematically addressed in clinical research and practice Those issues have now been addressed and actigraphy may now be reaching the maturity needed for application in the clinical arena

The role of actigraphy in the study of sleep and circadian rhythms.

1.0 BACKGROUND ACTIGRAPHY HAS BEEN USED TO STUDY SLEEP/WAKE PATTERNS FOR OVER 20 YEARS. The advantage of actigraphy over traditional polysomnography (PSG) is that actigraphy can conveniently record continuously for 24-hours a day for days, weeks or even longer. In 1995, Sadeh et al.,1 under the auspices of the American Sleep Disorders Association (now called the American Academy of Sleep Medicine, AASM), reviewed the current knowledge about the role of actigraphy in the evaluation of sleep disorders. They concluded that actigraphy does provide useful information and that it may be a “cost-effective method for assessing specific sleep disorders...[but that] methodological issues have not been systematically addressed in clinical research and practice.” Based on that task force’s report, the AASM Standards of Practice Committee concluded that actigraphy was not indicated for routine diagnosis or for assessment of severity or management of sleep disorders, but might be a useful adjunct for diagnosing insomnia, circadian rhythm disorders or excessive sleepiness.2 Since that time, actigraph technology has improved, and many more studies have been conducted. Several review papers have concluded that wrist actigraphy can usefully approximate sleep versus wake state during 24 hours and have noted that actigraphy has been used for monitoring insomnia, circadian sleep/wake disturbances, and periodic limb movement disorder.3,4 This paper begins where the 1995 paper left off. Under the auspices of the AASM, a new task force was established to review the current state of the art of this technology.

The Role of Actigraphy in the Study of Sleep and Circadian Rhythms AMERICAN ACADEMY OF SLEEP MEDICINE REVIEW PAPER

Auditory and non-auditory effects of noise on health

Noise is pervasive in everyday life and can cause both auditory and non-auditory health eff ects. Noise-induced hearing loss remains highly prevalent in occupational settings, and is increasingly caused by social noise exposure (eg, through personal music players). Our understanding of molecular mechanisms involved in noise-induced haircell and nerve damage has substantially increased, and preventive and therapeutic drugs will probably become available within 10 years. Evidence of the non-auditory eff ects of environmental noise exposure on public health is growing. Observational and experimental studies have shown that noise exposure leads to annoyance, disturbs sleep and causes daytime sleepiness, aff ects patient outcomes and staff performance in hospitals, increases the occurrence of hypertension and cardiovascular disease, and impairs cognitive performance in schoolchildren. In this Review, we stress the importance of adequate noise prevention and mitigation strategies for public health.

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Auditory and non-auditory eff ects of noise on health

Sleep and circadian rhythm disruption are frequently observed in patients with psychiatric disorders and neurodegenerative disease. The abnormal sleep that is experienced by these patients is largely assumed to be the product of medication or some other influence that is not well defined. However, normal brain function and the generation of sleep are linked by common neurotransmitter systems and regulatory pathways. Disruption of sleep alters sleep-wake timing, destabilizes physiology and promotes a range of pathologies (from cognitive to metabolic defects) that are rarely considered to be associated with abnormal sleep. We propose that brain disorders and abnormal sleep have a common mechanistic origin and that many co-morbid pathologies that are found in brain disease arise from a destabilization of sleep mechanisms. The stabilization of sleep may be a means by which to reduce the symptoms of--and permit early intervention of--psychiatric and neurodegenerative disease.

Sleep and circadian rhythm disruption in psychiatric and neurodegenerative disease

Partial sleep deprivation: impact on the architecture and quality of sleep

After time-zone flights, the environmental time is shifted abruptly. The sleep-wake cycle and the circadian system cannot follow this sudden phase shift. Therefore, some or several days are necessary to achieve complete adjustment to a new time zone. The effects resulting from the displacement between internal and external time are well known as jet lag. In principle, timed bright light is able to enhance the resynchronization process of the circadian system after advance or delay shifts. In this report, the effects of bright light exposure on circadian phases and amplitudes after real or simulated time zone transitions are reviewed from the accessible literature and are critically discussed. It can be concluded that laboratory studies have not been unequivocally successful to support the hypothesis that bright light alleviates jet lag. The sparse number of field studies do not yet allow a clear judgment on the beneficial effect of bright light treatment on jet lag.

Bright light: a countermeasure for jet lag?

A two-phase study was performed on B-747 crew members operating on regular passenger flights with 9-h time difference. In phase I, sleep-log surveys were obtained. The results for the layover period indicate congruent sleep patterns with shifts in sleep onset less than 9 h; sleep duration was prolonged. Phase II consisted of polygraphic sleep recordings and multiple sleep latency tests (MSLTs) applied to four cockpit crews in a baseline period, during the layover, and after return to home base. During the layover, mean bed times were shifted by about 4.5 h, and sleep was disturbed by early and prolonged awakenings which led to a reduction of sleep efficiency. The ECG and rectal temperature recordings gave evidence for a desynchronization of the circadian system and an internal dissociation of different body functions.

Sleep, sleepiness, and circadian rhythmicity in aircrews operating on transatlantic routes.

INTRODUCTION: Helicopter-based emergency medical services in Germany operate from sunrise to sunset, requiring up to 15.5 h of continuous duty during the summer months for pilots, who work for seven consecutive days. Because of concerns regarding the safety of this procedure with respect to pilot fatigue and stress, the German Ministry of Transport asked our laboratory to investigate the risks involved. METHODS: There were 13 pilots (mean age 38 yr) who were studied in the summer months for 2 d before, 7 d during, and 2 d after their duty cycle. Measured variables included sleep duration and quality, subjective fatigue, and heart rate, as well as 24-h excretion levels of stress hormones. RESULTS: During actual helicopter operations, maximum heart rates did not exceed 120 bpm. Over the 7-d duty period, mean sleep duration decreased from 7.8 h to 6 h or less, resulting in a cumulative sleep loss of about 15 h. Mean levels of excreted adrenalin, noradrenalin, and cortisol increased significantly by 50 to 80%; cortisol and noradrenalin excretion also remained elevated for the two post-duty days. CONCLUSIONS: Although the actual flights did not cause critical physiological responses, the acute and accumulated sleep deficit led to incomplete recuperation between duty hours and induced elevated stress indicators. It was, therefore, recommended that the duty cycle be amended as follows: 1.) enforce a 10-h rest period and at least an 8-h sleep opportunity per day; 2.) modify the duty period to allow no more than 3 consecutive rest periods of reduced sleep opportunities (8.5 h); and 3.) follow duty with several days that offer unrestricted sleep opportunities. Language: en

Sleep deficit and stress hormones in helicopter pilots on 7-day duty for emergency medical services

INTRODUCTION: It is a well known fact that noise annoyance depends on the traffic mode. Much less is known about differences in physiological effects, especially on combined effects. Therefore, we investigated the effects of air (AI), road (RO) and rail (RA) traffic noise on sleep in the AIRORA study. METHODS: 72 subjects (40 ± 13 years, 32 male) were polysomnographically investigated during 11 consecutive nights in the laboratory. Electrophysiological signals included EEG, EOG, EMG, EKG, respiratory movements and finger pulse amplitude. Cortisol and noradrenalin were measured in nocturnal urine samples. Each traffic mode consisted of five noise categories (maximum SPL 45, 50, 55, 60 and 65 dBA) with 8 different noise events, i.e. 40 noise events in total. Therefore, between 40 and 120 noise events were realistically played back during single (AI, RO, RA, RORO), double (AIRO, AIRA, RORA) and triple (AIRORA) exposure nights. The design was complemented with a noise-free control night and carefully balanced. RESULTS: Annoyance due to aircraft noise was stronger compared to both rail and road traffic noise. However, according to multvariable random subject effect logistic regression models, awakening probability increased in the order AI, RO, RA (AI<RO, AI<RA, both p<0.0001; RO<RA, p=0.513). Cumulative effects in double and triple exposure nights were both lower (S1, SWS) and higher (Wake, REM) compared to expectations based on single exposure nights. Nocturnal traffic noise exposure had no influence on stress hormone excretion rates. CONCLUSIONS: Traffic modes differ in their noise effects on sleep. Field studies are needed to validate our results.

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Alexander Samel

Papers

Partial sleep deprivation: impact on the architecture and quality of sleep

Bright light: a countermeasure for jet lag?

Sleep, sleepiness, and circadian rhythmicity in aircrews operating on transatlantic routes.

Sleep deficit and stress hormones in helicopter pilots on 7-day duty for emergency medical services

Single and combined effects of air, road and rail traffic noise on sleep