I need to build a simple accelerometer wrist watch to record hand or leg movements during sleep and get ( X,Y Z) data. How can I start with this ?
Get an accelerometer.
ok , what is next after getting an accelerometer , what else I need, how can I get data from it ?
Learning how to use Google is always a good place to start and if you'd read the "how to use this forum" sticky, you'd have learned that you are expected to do some Googling of your own before you come here.
In case you have been in an isolation ward for the last 20 years and are new to internetz, some suggestions regarding searching... Keep your searches simple. For example, first try the keyword Arduino, followed by one or two other keywords at most will usually turn up lots of good info that will give you ideas for additional keywords to use. Searching for arduino accelerometer turns up many useful hits. Searching for arduino accelerometer wrist watch gives fewer hits but, amazingly, you aren't the first person in the history of the world to have the idea.
Also, I've found good tutorials by the vendor called Adafruit. They aren't the cheapest supplier (compared to, say, eBay), but if you use their tutorials and libraries, it is nice to support them. And yes, they do sell accelerometers.
One of your problems will be to "miniaturize" your system. Worry about that later - first get a prototype working.
Accelerometer, Nano, 9V, and effort. Get those.
There are plenty of tutorials on Adafruit and Sparkfun to tell you how to hook an acceleromter to an arduino and get data from it.
Just what is your level of knowledge here?
If I found answer on google I wouldn't post a question , anyway thanks for help.
May be FLORA Accelerometer is good option to start with it , but how can I deal with the power source if I
design it as a wrist accelerometer ?
Use a small battery.