Your sleep schedule being off could be a result of your lack of exercise. I know for me it works this way, at least.

I have the Gold's Gym adjustable weights, that go from 10-50 lbs, but I don't recommend them. The weights stick too much and sometimes the plates fall off and onto my foot. Ouch! I also have a set of Reebok ones that range from 2.5-12.5 lbs. Those are good.

I'd suggest going for the Selectech ones. They're more expensive, but I'm sure they wouldn't be such a pain to work with. The extra $ will be worth it!

I looked up the selectech... there's a set on craigslist where I am for BIG money... used even. I saw a Sale going on at sears, they're got a set for sale that was like 197 or something. not sure if they're the same as the Gold's Gym ones, but I'm highly contemplating it.