To the Editor Ju et al1 reported objective sleep for 142 patients (58 men and 84 women) with preclinical stage Alzheimer disease. The mean (SD) age of the patients was 65.6 (8.2) years old. Among them, 32 patients presented with β-amyloid 42 levels in cerebrospinal fluid of 500 pg/mL or less. The authors used wrist actigraph Actiwatch 2 (Philips Respironics), and sleep efficiency and total sleep time were used as the main sleep indicators. They concluded there was a significant decrease in sleep efficiency observed in the group with lower β-amyloid 42 levels. In contrast, there was no significant difference in the mean value of total sleep time between groups stratified by β-amyloid 42 level.
Kawada T. Sleep Evaluation by Actigraphy for Patients With Alzheimer Disease. JAMA Neurol. 2013;70(8):1074. doi:10.1001/jamaneurol.2013.3163