William J. Mason

Sleep estimation from wrist movement quantified by different actigraphic modalities

Progress in transducer design and empirical characterization of wrist movement has led to diverse wrist activity monitors, each with its unique features and modality of operation. This study compared sleep--wake estimates from nocturnal wrist activity quantified by different motion-quantifying algorithms. Healthy young adults wore an Actillume and a Mini Motionlogger on the same wrist while nocturnal polysomnography data were recorded simultaneously in the laboratory. Activity data were analyzed with ACTION3 using scoring algorithms independently calibrated for each measurement modality. Overall, each modality yielded accurate and reliable sleep estimates relative to polysomnographic estimates (agreement rates: 91.4--96.5%, correlations for sleep duration: 0.79--0.94). Estimates derived from Actillume modalities were comparable to those of Mini Motionloggers, suggesting that the transducers of these two devices performed comparably for monitoring sleep and wakefulness. Wrist movement quantified by the Mini Motionlogger proportional-integrating mode yielded the best accuracy for detection of sleep--wake states.

Low illumination experienced by San Diego adults: Association with atypical depressive symptoms☆

We explored the illumination exposure of middle-aged adults to determine normal values and to explore several correlates of daily light exposures. Subjects aged 40-64 years in San Diego, CA were recruited by random telephone dialing. Subjects completed a demographic interview and the Center for Epidemiologic Studies Depression self-rating scale (the CES-D) supplemented with eight questions related to seasonal affective disorders (SAD). Data were analyzed for 106 volunteers who wore a device that monitors illumination exposures and activity. The median subject was exposed to illumination > or = 1000 lux for only 4% of the time observed, that is, only about 58 min per day were spent in daylight. Subjects scoring higher on the atypical SAD mood symptoms spent less time in bright illumination rs = -0.266, p = 0.003. The CES-D depression score was similarly correlated with illumination but of borderline significance (rs = -0.150, p = 0.063). These results suggest the hypothesis that many Americans may be receiving insufficient light exposure to maintain optimal mood.

Long-term follow-up of sleep disordered breathing in older adults.

OBJECTIVE The current study was designed to determine whether, with increasing age, sleep apnea improves, becomes worse, or stays the same. BACKGROUND There is a high prevalence of sleep disordered breathing (SDB) in older adults, but little is known about longitudinal changes. This study followed older adults to examine the natural history of SDB. METHODS Subjects were randomly selected community-dwelling elderly (n=427). A subset of subjects was studied approximately every 2 years over an 18-year period. Overnight sleep recordings and sleep questionnaires were completed at each time point. RESULTS Multiple linear regression showed that three variables were associated with change in respiratory disturbance index (RDI):body mass index (BMI) at initial visit (P=0.001), change in BMI (P=0.02), and a consistent self-report of high blood pressure (P=0.005). RDI increase was associated with BMI increase and presence of self-reported high blood pressure. CONCLUSIONS The changes in RDI that occurred were associated only with changes in BMI and were independent of age. This underscores the importance of managing weight for older adults, particularly those with hypertension.

Characteristics of obstructive and central sleep apnea in the elderly: An interim report

Home sleep recordings were done on 358 randomly selected elderly volunteers (mean age 72.4). When men and women were combined, 62 (17%) had predominantly obstructive sleep apnea, 21 (6%) had predominantly central sleep apnea, and 3 (1%) had mixed sleep apnea. Although the prevalence of sleep apnea in women does increase after menopause, sleep apnea was still significantly more common in older men (31%) than in older women (19%). There were no significant differences in age among groups with different types of apnea. There was a significant correlation of age with increasing apnea index within the obstructive sleep apnea group. Elderly volunteers with central sleep apnea had more midsleep awakenings. Elderly volunteers with obstructive sleep apnea had longer apneas. Unlike previous studies, we found many similarities and only modest differences in the presentations of central and obstructive sleep apnea.

Evaluation of sleep disordered breathing with unattended recording: the Nightwatch System

There is a need for studies to determine how new ambulatory systems compare to traditional polysomnography (PSG). Thirty-four subjects were recorded with the Nightwatch (NW) System (Heathdyne Inc.) at home and then recorded with PSG in the laboratory. NW records were scored automatically using the NW algorithm with manual editing. There were no significant differences in mean RDI, AI, number of apneas or hypopneas or oximetry varibles between the systems. Correlations of RDI on the Nightwatch system and laboratory nights were significant (r = 0.63). Every case of RDI > or = 10 on the PSG was also identified by Nightwatch. Specificity was lower on Nightwatch (66%); however, all three cases of false positives could be explained physiologically, i.e. by body position. Overall the NW system correlated well with traditional PSG for respiratory disturbance.

The Application and Utilization of an Ambulatory Recording System for the Screening of Sleep Disorders

ABSTRACT.It has become apparent in the last few years that many sleep complaints expressed by patients may involve cessation of breathing during sleep (apnea) or severe leg jerks (periodic movements in sleep-PMS), causing brief arousals throughout the night. The most commonly used practice for screening of these two disorders has been an all-night laboratory polysomnogram, which records sleep/wake, respiration, and leg movements. This technique involves, for the patient, a high cost, restriction of movement, and an unfamiliar and sometimes frightening setting. During the last few years our laboratory has used a portable ambulatory recording method to screen for sleep apnea and PMS, establishing a reliable and comfortable screening procedure in the patients own home. The overall cost of an initial screening is thus reduced, as is the time spent by the technician who, in the laboratory, would monitor the patient all night. This method allows more patients to be screened by one technician and allows easy ap...

Relationships Among Illumination, Activity, and Sleep Patterns

Diverse strategies for optimal light treatment of individuals with circadian and/or seasonal disorders have been generated4,7. Yet, little is known about actual environmental illumination in the population. Using Actillumes, our laboratory has shown that illumination exposure experienced by San Diego adults5 and Rochester residents3 were often lower than intensities needed for robust circadian phase-shifting4. However, illumination of lower intensity influences circadian rhythms1,10