Abstract
Purpose: :
Evidence suggests that visual impairment is associated with decreased physical activity, and depression has a negative effect on physical activity. The purpose of this study is to examine the association of visual impairment with rest-activity cycles using actigraphic data.
Methods: :
Data were collected from sixty older adults (69 ± 6 yrs) who participated in a study investigating relationships between visual dysfunction and circadian rhythms. Of the sample, 33 were black and 27 were white [women; 71%]. During face-to-face interviews, participants provided physical health data using the Comprehensive Assessment & Referral Examination. They also provided mood ratings using the Geriatric Depression Scale (GDS). Participants were examined by an ophthalmologist and wore an actigraph (Actiwatch-L) for 1 week providing rest-activity recordings. The mesor and acrophase of rest-activity data were determined using cosine analysis. Sleep measures were estimated using software provided by the manufacturer (Mini-Mitter).
Results: :
Participants (85%) reported being in good health; 14% received an eye diagnosis, but none were legally blind. Participants had an average BMI and GDS score of 27.68±5.72 and 7.83±4.74, respectively. The average sleep time, time to bed, and time out of bed were 8.35±3.20; 22.75±1.67; and 6.89±2.49, respectively. MANOVA results revealed that visual impairment had a significant effect on the level and timing of rest-activity cycles [F=5.54, p=0.02; F= 11.86, p=0.01, respectively]. Results of the factorial MONOVA indicated a significant interaction between visual impairment and depression on the mesor of rest-activity [F=4.29, p=0.04]. With control for depression, a significant correlation between visual impairment and rest-activity timing was found [rp=-0.33, p=0.01], whereas controlling for visual impairment yielded no significant correlation between activity timing and depression [rp=0.20, p=0.13].
Conclusions: :
Results suggest that visual impairment mediated associations between depression and rest-activity. Treatment of individuals who are visually impaired may lead to improved rest-activity cycles, thereby decreasing negative moods.
Keywords: quality of life • vision and action • circadian rhythms