to use threads, i could implement all methods on the same file?

i mean, i have one file with 5 diferent methods, all of them have a "while true" inside it, and inside the "While true" i have a "Thread.CurrentThread.Sleep(5000)" to sleep for 5 seconds each thread. Have some problem with it??

I think it have some problem, because it uses betwen 95% and 98% of the cpu!

Thank you,
Guilherme Costa