This article is from the Ergonomics and Typing Injury FAQ, by Dan Wallach firstname.lastname@example.org with numerous contributions by others.
Various sources, e.g. Casio BP-100.
Many digital watches have timers that count down from a settable number of
minutes; they usually reset easily to that number, either manually or
While these are a very basic tool, they are very useful if you are
writing, reading, driving, or doing anything away from a computer which
can still cause or aggravate RSI. The great advantage is that they remind
you to break from whatever you are doing.
My own experience was that cutting down a lot on my typing led to my
writing a lot more, and still reading as much as ever, which actually
aggravated the RSI in my right arm though the left arm improved.
Getting a count-down timer watch has been very useful on some
occasions where I write a lot in a day.
I have tried an old fashioned hour-glass type egg timer, but these
are not much good because they do not give an audible warning of the
end of the time period!