Methods, systems and devices configured to add synchronization to the entry and exit from low power modes in asynchronous operating systems on a multiprocessor system. A synchronizing agent tracks the requested sleep and wake up times of the different asynchronous operating systems executing on different cores of the same system on chip or multicore processor. The sleep/wake up times of some cores/operating systems may be delayed in order to synchronize the sleep/wake up times of two or more of the asynchronous operating systems executing on the multiprocessor system.