What is ReentrantLock#tryLock(long,TimeUnit) doing when it tries to aquire the lock?

What is the ReentrantLock#tryLock(long,TimeUnit) implementation doing when it tries to aquire a lock ? Assume Thread A acually owns the Lock of myLock, and Thread B call myLock.tryLock(10,SECONDS), is Thread B sleeping or waiting ?

In other words, was is the difference of this 2 implementations:

1.

while (true)
   try {
     if (readLock.tryLock())
       return;
     MILLISECONDS.sleep(5);
   }catch (InterruptedException e) {}

2.

 while (true)
   try {
     if (readLock.tryLock(5,MILLISECONDS))
       return;
   }catch (InterruptedException e) {}