c# - Efficiency of DispatcherTimer versus Thread.Sleep -

what more efficient use, dispatchertimer or thread.sleep in c#?

i use dispatchertimer:

 dispatchertimer timer = new dispatchertimer();  timer.interval = timespan.fromseconds(20);  timer.tick += timer_tick;  timer.start(); // every 20 seconds 

or, use thread.sleep:

 while(true) {     thread.sleep(20000);     // every 20 seconds  } 

in cases should use them? there best practices?

edit: based on first answers, need add application developing has no ui (so blocking thread no issue), background tracker, writes data logfile.

the dispatchertimer invoke method on ui thread every n [unit of time]. thread.sleep sleep thread completely. difference former, thread continues, invokes tick event , latter stops thread doing anything.

it's important realise ui thread busy rendering ui , running code; hence, sleep in ui thread perceived application hang.