Why is Thread.Sleep so harmful

Question

I often see it mentioned that Thread.Sleep(); should not be used, but I can't understand why this is so. If Thread.Sleep(); can cause trouble, are there any alternative solutions with the same result that would be safe?

eg.

while(true)
{
    doSomework();
    i++;
    Thread.Sleep(5000);
}

another one is:

while (true)
{
    string[] images = Directory.GetFiles(@"C:\Dir", "*.png");

    foreach (string image in images)
    {
        this.Invoke(() => this.Enabled = true);
        pictureBox1.Image = new Bitmap(image);
        Thread.Sleep(1000);
    }
}

Answer 1

SCENARIO 1 - wait for async task completion: I agree that WaitHandle/Auto|ManualResetEvent should be used in scenario where a thread is waiting for task on another thread to complete.

SCENARIO 2 - timing while loop: However, as a crude timing mechanism (while+Thread.Sleep) is perfectly fine for 99% of applications which does NOT require knowing exactly when the blocked Thread should "wake up*. The argument that it takes 200k cycles to create the thread is also invalid - the timing loop thread needs be created anyway and 200k cycles is just another big number (tell me how many cycles to open a file/socket/db calls?).

So if while+Thread.Sleep works, why complicate things? Only syntax lawyers would, be practical!