Please help me solve this problem.

I create an QT application has a QThread. In run function, use QThread::sleep in while(1) loop. I put qDebug before call sleep. When i run the program. the 'sleep' log will print out every 1 second. 
After that, i change system time by command timedatectl set-time '2015-11-23 08:10:40'.
Now, 'sleep' log is not print out anymore! 

```
void TestThread::run()
{
    while (1) {
        qDebug() << "sleep";
        sleep(1);
    }
}

```

Thanks for your help!