Comparative analysis of actigraphy performance in healthy young subjects

Abstract

Sleep-related health disorders are increasing worldwide; diagnosis and treatment of such sleep diseases are commonly invasive and sometimes unpractical or expensive. Actigraphy has been recently introduced as a tool for the study of sleep and circadian disorders; however, there are several devices that claim to be useful for research and have not been thoroughly tested. This comparative study provides activity, sleep and temperature information regarding several of the most commonly used actigraphers: Micro-Mini Motion Logger; Act Trust; Misfit Flash; Fitbit Flex & Thermochron. Twenty-two healthy young subjects were assessed with five different commercial actigraphs (Micro-Mini Motionlogger Watch, Condor Act Trust, MisFit Flash and Fitbit Flex) and a temperature recorder (Thermochron), and also completed a sleep diary for a week. There were not significant differences in the analysis of rest-activity pattern between devices. Temperature rhythm comparison between the Act Trust and the Thermochron showed significant differences in rhythm percentage (p<0.05) and mesor (p<0.0563) but not in amplitude or acrophase. Although data accessibility and ease of use was very different for the diverse devices, there were no significant differences for sleep onset, total sleep time and sleep efficiency recordings, where applicable. In conclusion, depending on the type of study and analysis desired (as well as cost and compliance of use), we propose some relative advantages for the different actigraphy/temperature recording devices.

Keywords: Actigraphy; Ambulatory monitoring; Circadian; Rest-activity; Sleep; Temperature.

Fig. 1

Representative actograms for 5 days (3 weekdays and 2 weekend days, i.e. Wed-Fri., Sat-Sun.) for activity counts extracted from Micro-Mini Motionlogger (MM), Act Trust (CAT), Misfit Flash (MF) and Fitbit Flex (FF) devices. Triangles represent temperature acrophases assessed from CAT and Thermochron TH devices.

Fig. 2

Activity onset calculation. Left panel: Average activity onset for weekdays and weekend from Micro-Mini Motionlogger (MM), Act Trust (CAT), Misfit Flash (MF) and Fitbit Flex (FF) devices. Two-way ANOVA shows only significant differences between weekdays and weekends (***p<0.001). Right panel: Relative activity onset (activity onset for each device – activity onset of the sleep diary) analysis shows significant differences for MF compared with MM and CAT. One-way ANOVA (p=0.0128) followed by Tukey's multiple comparison test (*p<0.05).

Fig. 3

Sleep onset, total sleep time and sleep efficiency analysis. Top panel: Correlation curves for Micro-Mini Motionlogger (MM), Act Trust (CAT) and Misfit Flash(MF) devices. Sleep onset exhibited very good correlation for all the devices. Middle panel: Correlation curves for Micro-Mini Motionlogger (MM), Act Trust (CAT) and Misfit Flash (MF) devices for total sleep time evidenced very good correlation for all the devices. Bottom panel: Correlation curve for Micro-Mini Motionlogger (MM) and Act Trust (CAT) devices. Sleep efficiency estimates indicated a low correlation between the different devices. Graph insets indicate Pearson's r correlation values and p bilateral significance values (r and p respectively).

Fig. 4

Bland – Altman assessing the limits of agreement between sleep onset (top panels), total sleep time (TST, middle panel) and sleep efficiency (SE, bottom panel). Solid lines represent the mean difference, while dashed lines represent mean difference +/– 2 standard deviations.

Fig. 5

Sleep onset, total sleep time and sleep efficiency analysis. Mean sleep onset (top panel) and total sleep time (middle panel) from Micro-Mini Motionlogger (MM), Act Trust (CAT) and Misfit Flash (MF) analysis indicated no significant differences between the devices (ANOVA (p=0.0697 and p=0.2446 respectively). Lower panel: there were no significant differences for sleep efficiency between Micro-Mini Motionlogger (MM) and Act Trust (CAT) devices (n.s., Student's t test), although ANOVA indicated significant differences in their variance (p<0.0001).