I've seen a lot of those things (Hacker News has in the past week been discussing some new product which doesn't use a cellphone but you wear on your wrist as a band). I'm not sure how good their data is.

I do plan to get a Zeo (from Zeo Inc., since they seem to provide much better data on your sleep (such as what stage you are in, which would be very important if one wanted to run polyphasic experiments) - but I'm torn between that and SNP/DNA testing from 23AndMe to learn about how effective modafinil might be for me.

EDIT: I got a Zeo and have been happily running experiments, see http://lesswrong.com/lw/1lt/case_study_melatonin/5w76 ; so now I guess I need to figure out what the right price to me for SNP testing is. And also how to legally get it where I am...