EFFECT OF LIGHT ON MELATONIN IN THE INSTITUTIONALIZED ELDERLY (NURSING HOMES, ILLUMINATION, CIRCADIAN RHYTHMS).
Contributors: University Of California, San Diego And San Diego State University.
Published: 1993
Number of pages: 94
Subjects: Psychology, Clinical.
Description: Sleep in nursing home residents is highly fragmented. Disturbed circadian rhythms may be a partial cause. Melatonin, a pineal hormone, is a marker of circadian rhythms. Its secretion is synchronized by light. Nursing home residents are exposed to low levels of illumination. Therefore, some of this disrupted sleep may be secondary to their low illumination exposure. The present study simultaneously measured illumination exposure, melatonin secretion and sleep fragmentation in nursing home residents to determine whether low illumination exposure and melatonin secretion are associated with fragmented sleep. Ten subjects were recruited from a nursing home sample. Each subject participated in two 3-day blocks of 48 hours of Actillume baseline and 24 hours of Actillume plus urine collection. Bright light treatment was administered between 1730 and 1930 during one of the 24 hour urine collection periods. Cosinor analyses were performed on the light, sleep and melatonin variables. A two-way Anova (treatment by order) contrasted the light condition with the order of light treatment (study night one or study night two). Results showed (1) no significant difference in light mesor, amplitude, or phase between the bright light and the natural conditions, (2) no significant difference in sleep mesor, amplitude or phase between the bright light and natural conditions, and (3) no significant differences in melatonin mesor, amplitude, and phase contrasting bright light and natural light.

Finally, descriptive statistics regarding sleep, light exposure and melatonin levels indicated: (1) sleep was highly fragmented in this nursing home sample, (2) light exposure was quite low and (3) a lack of difference in melatonin secretion between 6pm-6am and 6am-6pm was noted. The lack of difference in melatonin secretion between 6pm-6am and 6am-6pm may be associated with disturbed sleep and low illumination exposure. Directions for future research are discussed.
Notes: Source: Dissertation Abstracts International, Volume: 54-09, Section: B, page: 4920.

Thesis (PH.D.)--UNIVERSITY OF CALIFORNIA, SAN DIEGO AND SAN DIEGO STATE UNIVERSITY, 1993.

School code: 0385.