title: How to sleep a C++ Boost Thread
body: <p>Seems impossible to sleep a thread using boost::thread.
  Method sleep requires a system_time but how can I build it?</p>
  
  <p>Looking inside libraries doesn't really help much...</p>
  
  <p>Basically I have a thread
  inside the function that I pass to this thread as entry point, I would like to call something like </p>
  
  <pre><code> boost::this_thread::sleep
  </code></pre>
  
  <p>or something, how to do this?</p>
  
  <p>Thank you</p>