c++11 thread sleep/wakeup without lock?

I use a lockfree queue between two threads. One produce data,another consume data. What I want to do is that, when the queue is empty, consumer thread yield cpu until producer thread push data to the queue. I can't call sleep() since there is no way to wakeup a sleeping thread, I think. What I found is std::condition_variable, but it needs a mutex. producer thread need to hold the lock and then notify consumer thread for every data pushing. Is there a better and lighter way to realize my goal?