ACTman: Automatic Event marker to Sleep log Functionality

Expanding ACTman's possibilities

Hi guys, I am excited to present to you here, our newest update for our ACTman package!

As you might know, we introduced the ACTman software for R as a useful tool for both preprocessing as well as analysis of actigraphy data. Hopefully ACTman will facilitate easier, quicker, and better reproducible actigraphy analyses.

A new piece of functionality we just added - and which I am very enthousiastic about - is the possibility to read in event marker files and automatically convert them to sleep logs within mere seconds!

This is an especially handy tool for those researchers who use the marker button to estimate the times of going to bed and getting out of bed. Instead of manually writting these times down, participants can just simply press the event marker.

And instead of having to manually transcribe the event marker times to a generic sleeplog, you can now have ACTman do it for you in a quick and reproducible manner!

And the best part is that you don't have to do anything special for it. 

If you are using the MotionWatch 8, and ACTman detects no sleeplog in your working directory but does detect a marker file, it will automatically transform it to a sleeplog for you.

You also get user control over some decisions. For example, if marker buttons are missing, ACTman offers you the choice to fill them in yourself, fill in the missing value with a mean value, or to abort the analysis.

Furthermore, ACTman automatically removes any other marker between the first and lst mrker press of that day. Multiple false presses are thus no problem for ACTman.

Interested? Check ACTman out for yourself by clicking here!

Buyers Guide: Actigraphs

Points to consider

One of the most common questions I get from fellow scholars is: "Which Actigraph is most suitable for my study?".

However, it is hard to give a simple and straightforward answer, as the optimal choice for your situation depends on your study design, e.g.,  study duration, sample characteristics, analysis goals, et cetera.

As such I have compiled some points which should be considered when choosing an actigraph for academic purposes:

1. Does the considered actigraph provide you with the raw data?

This is one of the most important points when considering actigraphs for academic purposes, and one of the most overlooked ones. 

"Why is this so important?", you might ask. Well, when the raw data is not provided, the data can be somewhat akin to a black box. That is, you will have no idea what happened to the data beforehand. Perhaps the manufacturer uses a transformation on the data, or perhaps some smoothing functions. This will often be documented very sparsely, if at all.

As such, you will have at best only a partial idea of what your data respresents, possibly obfuscating your results, and your control over your own study.

Hence, when a device offers you access to the raw data you will have a better idea what happened to it and what it really means.

2. In what kind of unit will the actigraph measure?

This point is very much related to the first one. There are various units in which the actigraph can deliver its data. For example gravity units, activity 'counts', and manufacturer-specific units.

txt

3. How long will the considered actigraph last before it needs new batteries?

This is an important point as battery issues can seriously hamper the quality of your dataset. Even worse, the maximum battery duration given by the manufacturer might well be an overstatement which fails to materialise under normal conditions.

In the case of one of our own studies we were once confronted with an actigraph which boasted a battery life of 4 months. As such, we designed our whole study around this period. Hence our dismay when participants returned en masse with their empty actigraphs after a mere 2 months.

Thus, we had to make an ad hoc change to our design wherein we sent participants a new actigraph near the 2 months mark. This lead to unexpected costs for sending devices, an extra burden for participants, and worst of all missing data.

Therefore, make sure you know and test the actual battery life when considering an actigraph for your study!

4. User comfort and material safety

txt