Alternate to Thread.Sleep

I coded this small stub to waste time as an alternate to Thread.Sleep:

private void WasteTime(TimeSpan unit)
{
  DateTime now = DateTime.Now;
  DateTime then = DateTime.Now + unit;

  while (now < then)
  {
    now = DateTime.Now;
  }
}

Works quite preceisely.

private void WasteTime(TimeSpan unit)
{
  DateTime then = DateTime.Now + unit;
  while (DateTime.Now < then)
  {;}
}