Validation of the Actiwatch for older people with intellectual disability; a feasibility study

In the *Healthy aging with an intellectual disability study* (GOUD, METC
2008-234, NL 23941.078.08) the Actiwatch (Cambridge Neurotechnology Ltd,
Cambridge, United Kingdom) was used to investigate the rest - activity pattern.
This instrument is increasingly used in sleep research. The Actiwatch is a
small watch-like device which contains an accelometer, and is worn on the
wrist. It is non-invasive and can be used in the home environment. To register
sleep, the Actiwatch Sleep Analysis software uses an algorithm that looks at
each data point and calculates a total score, based on the activity counts from
each epoch and those surrounding it. The software provides four sensitivity
settings to analyze the data files: low sensitivity= 80 counts per epoch,
medium sensitivity=40 counts per epoch, high sensitivity=20 counts per epoch
and auto sensitivity=variable counts per epoch (the auto sensitivity setting
approximates the medium sensitivity setting). At the low sensitivity setting
(80 counts per epoch) more movement is necessary to score an epoch as awake,
than at the high sensitivity setting (20 counts per epoch). For example when
the sensitivity setting is set on medium, an epoch is scored as *asleep* when
the total activity score is <40 counts, and awake when the total activity score
exceeds 40 counts per epoch. To gain first information on the applicability and
outcomes of the Actiwatch in older people with intellectual disability, data
collected in the first year of GOUD were analyzed for the low and high
sensitivity setting. The first results show that the chosen sensitivity setting
has major influence on the values of different sleep parameters. In order to
make the right choice for sensitivity setting we want to validate the Actiwatch
with sleepregistration (golden standard) for older people with intellectual
disability. The feasibility of EEG-investigation in older people with
intellectual disability is investigated.

The first objective of this study is to investigate the feasibility of
performing home sleep EEG registrations in older people with intellectual
disability. The second objective of this study is the determine which
sensitivity setting of the Sleep Analysis software gives
most valid results, in favor of the data analysis of the healthy aging (GOUD)
study.

Pilot study with a cross-sectional design

Participants will be measured for 48 hours with two types of Actiwatch (on the
wrist) and with sleepregistration (electrodes on head and face). The
measurement takes place in the home environment of the participant, so there is
no need for an overnight sleep in a sleep laboratory.
Participants have to be able to understand the measurements and give informed
consent themselves.
Burden can occur in terms of experiencing discomfort of the sleepregistration
electrodes and the data recorder. There is a small risk of skin irritation
caused by the Actiwatch or skin electrodes.