Faculty Bibliography

PURPOSE: To report the onset and progression of retinal nerve fiber layer myelination in an adolescent patient. METHODS: Case report. RESULTS: A 7-year-old male was found to have myelination of the retinal nerve fiber layer in the left eye. When he was reexamined at age 14 years, he was found to have new myelination in the right eye, progression of the myelination in the left eye, and bilateral optic nerve drusen. CONCLUSION: Retinal nerve fiber layer myelination can occur spontaneously in adolescence, progress in adolescence, and be associated with optic nerve drusen.

Actigraphy has been used to monitor individuals' sleep and wakefulness patterns without laboratory confinement. To date, its validity in monitoring sleep and wakefulness among patients with major depressive episodes has not been systematically examined. The present study investigated whether the normative criteria of the Actigraph Data Analysis Software, initially optimized for healthy individuals, could score wrist-activity data accurately in a sample of depressed patients. Application of the normative algorithm yielded a correlation coefficient of 0.85 and an average error of 35 min, comparing actigraphic and polysomnographic sleep estimates. The algorithm optimized for this sample provided a correlation coefficient of 0.81 and an error of 6 minutes. For both algorithms, agreement for individual comparisons varied substantially. These findings suggest that scoring criteria optimized on wrist-activity data of healthy young adults may not produce optimal results for patients characterized with major depressive episodes.

A recent report that popliteal illumination shifted the circadian rhythms of body temperature and melatonin challenged the longstanding belief that light phase-shifting the circadian system in mammals is mediated only through the retina. The authors tested effects of popliteal illumination and illumination provided through the eyelids on melatonin suppression. In randomized, counterbalanced orders, healthy volunteers received three treatments from midnight until 2:00 AM, one on each of three visits to the laboratory. Treatments included (1) no illumination from light pads applied to the popliteal fossae, with light mask maintained at < 3 lux (control); (2) light mask illuminated at 1700 lux, with popliteal light pads extinguished; and (3) popliteal light pads illuminated (13,000 lux) and light mask at < 3 lux (control). Saliva specimens were sampled at midnight, at 1:00 AM, and at 2:00 AM. Mean salivary melatonin concentrations rose from an average of 30.8 (3.9) pg/ml at midnight (baseline), to 33.2 (4.0) pg/ml at 1:00 AM, and to 37.2 (3.8) pg/ml at 2:00 AM in all three conditions, but no statistical differences were found using repeated-measures ANOVA. No evidence of melatonin suppression by either popliteal or closed eyelid light stimulation was found. These data suggest that bright retinal illumination is necessary for suppression of melatonin mediated through the suprachiasmatic nuclei.

BACKGROUND: Current knowledge of the population's sleep durations emanates primarily from questionnaires and laboratory studies. Using Actillumes, we investigated whether self-reported sleep durations were indicative of a population decline in sleep duration. We also explored illumination and activity patterns. METHODS: San Diego adults (n = 273, age range: 40-64) were recruited through random telephone calls and were monitored at home while engaging in usual daily routines. RESULTS: Volunteers slept an average of 6.22 hours and received an average of 554 lux (environmental illumination). The timing of sleep, illumination, and activity occurred at 2:44, 12:57, and 13:43, respectively. Irrespective of ethnicity, age, and time reference, men received greater illumination than did women, but this gender effect was not independent of work status. Women and men exhibited a similar circadian activity profile; however, women exhibited better sleep-wake patterns. Interactions between gender and ethnicity suggested worse sleep-wake patterns among minority men. An age-related decline in activity was found, but no age trend in sleep duration or illumination patterns was observed. CONCLUSIONS: This study showed an objective population decline in sleep duration. Sociodemographic effects should be considered in analyses of sleep-wake patterns and illumination exposures.

The Unified Biosocial Theory of Personality postulates that human personality is organized around four temperaments - Novelty Seeking, Harm Avoidance, Reward Dependence, and Persistence - and three characters - Self-Directedness, Cooperativeness, and Self-Transcendence. The objective of the present study was to investigate the influence of sociodemographic factors on temperament and character without the confounding influence of mental disorders. Volunteers (n=94) did not meet criteria for any Axis I and Axis II diagnosis, had no first-degree relatives with mental disorders, and were medically healthy. After giving written informed consent, volunteers completed the Temperament and Character Inventory. Analyses were conducted to determine the degree of association of each sociodemographic factor (i.e., age, gender, ethnicity, marital status, educational attainment, and occupational status) to personality dimension, while controlling for possible interactions with other sociodemographic factors. Partial correlation analysis showed a significant association between gender and Reward Dependence, and occupational status was significantly related to Reward Dependence, Cooperativeness, and Self-Transcendence. Stepwise regression analysis indicated that gender and occupational status were significant predictors of Reward Dependence. Occupational status was the only predictor of Cooperativeness and Self-Transcendence. These data suggest that sociodemographic factors should be considered in studies investigating temperaments and characters as defined by the Unified Biosocial Theory of Personality.

BACKGROUND: Circadian sleep-wake profiles in postmenopausal women were examined to explore relationships between nocturnal and out-of-bed sleep. METHODS: Twenty-one home recordings were obtained with unattended polysomnography from women ranging from 56 to 77 years of age. RESULTS: While maintaining their daily routines, volunteers slept an average of 439 minutes throughout the 24-hour recordings. Ten percent of the accumulated sleep time was recorded out of bed. CONCLUSIONS: Greater age was associated with more afternoon-evening sleep. Sleep was also frequently observed shortly after volunteers arose from bed in the morning.

Patterns of sleep, illumination, and activity of women of different ages were continuously monitored in their natural environments with a wrist activity monitor. Partial correlation analyses were performed to determine relationships between age and sleep and several circadian rhythm measures including the amplitudes, mesors, and timings of sleep, of illumination, and of activity. We found no age-related decline in actigraphic sleep duration. Age was not a significant correlate of circadian rhythm parameters of sleep. Moreover, no age effects were found on daily illumination exposure or on the circadian timing of illumination and activity patterns. However, the level and amplitude of the circadian activity rhythm showed a gradual decline with aging, independent of the time reference (i.e., Daylight Saving Time versus Standard Time) when recordings were obtained. As expected, significant associations were observed between local time reference and the level and timing of peak of illumination patterns. However, changes in local time reference were not significantly and consistently associated with actigraphic sleep or activity measures.

Researchers have found that melatonin substantially reduced both sleep onset latency and the number of nocturnal awakenings in normal individuals as well as patients with diverse sleep pathologies. These findings have led to an increase in the number of individuals who ingest melatonin habitually to alleviate their sleep problem. Given the widespread use of melatonin, it is important to identify the factors capable of predicting physiological states while following a melatonin regimen. The result of this preliminary analysis showed that the number of hours spent outdoors is the best predictor of subjective sleepiness while under the influence of melatonin. Specifically, the more time individuals spend outdoors, the sleepier they are when administered melatonin.

Research evidence suggests that actigraphy is a very important instrument in documenting sleep/wake patterns of people with a variety of sleep disorders or motor dysfunctions. The present actigraphic investigation examined physical activity and sleep profiles as a function of gender in volunteers monitored in their natural environment. Irrespective of age, women exhibited better sleep quality than did men. This was demonstrated by higher sleep efficiency index and lower frequency of transitions between sleep and wakefulness. Additionally, women slept more than men and had shorter sleep onset latency. However, no significant gender effect on daytime activity level and circadian activity amplitude was observed.

OBJECTIVE: Depressed mood is one of the essential features for the diagnosis of major depression. Evidence from the three-site Epidemiologic Catchment Area study (ECA, Baltimore, Durham and Los Angeles) suggests a prevalence of 4.4% of depressive symptoms in the community. In this study, we examined whether depressed mood, as coded in the Alzheimer's Disease Assessment Scale, would be correlated with actigraphic-derived daytime activity and sleep/wake parameters in a non-psychiatric sample. METHOD: Consenting volunteers were monitored at home for 5 days with a wrist actigraph. On the last day of the recording, they were given a neuropsychological battery including the Alzheimer's Disease Assessment Scale. RESULTS: Daytime activity level was the best predictor of depressed mood as indicated by a logistic regression analysis. The regression model further suggested that sleep onset latency, total time asleep, and time in bed were also significant predictors of depressed mood. CONCLUSION: This investigation demonstrates that daytime activity level could be used as an index of depressed mood even in a non-psychiatric sample. Further, the results support the notion that depression should be considered more as a continuum rather than as a set of rigid categories.