MW8 & MotionWare User Guide: Issue 1.2.1
Page 42
7 NPCRA Analysis
7.1 Introduction
Traditional analysis of circadian rhythms has attempted to
fit physiological indicators to a Cosine waveform shape
(Cosinor analysis). Activity-rest data do not typically fit well
with this type of analysis, hence the MotionWare software
provides the function of Non-Parametric Circadian Rhythm
Analysis (NPCRA). With this approach, we do not assume
that the data fit any pre-defined distribution. The method
used is to analyse full-days of data over several days to
determine some useful variables which are explained in
more detail below. Studies have shown that the non-
parametric variables are a valuable indicator of rhythm
disturbances caused by disease or aging and their
associated treatments.
7.2 Reference
The NPCRA analysis is based upon the work of Dr. Eus
Van Someren at the Netherlands Institute for Brain
Research
The original paper published by Dr. Van Someren is:
Van Someren, E J W, DF Swaab, C C Colenda, W
Cohen, W V McCall, and P B Rosenquist.
Bright
Light Therapy: Improved sensitivity to its effects on
rest-activity rhythms in Alzheimer patients by
application of nonparametric methods
.
Chronobiology Int. (1999)
16
(4) 505-518.
7.3 Analysis
NPCRA analysis requires complete data from as many full
days as possible. It is not recommended to attempt
analysis with less than 7 days of data and best results are
obtained with 14 or more days.
To select the analysis days, use the ‘Select All’ button in
the MotionWise screen to automatically select all available
days. Alternatively, use the ‘Select Days’ or ‘Select any’
tools to specify the analysis period (see Section 5.9
Selecting the Analysis Period).
Note also that the analysis is sensitive to periods of
inactivity when the MotionWatch has not been worn.
Having selected the analysis period, the analysis window
will be displayed. Sel
ect ‘NPCRA’ from the sidebar
functions.
