When configured, the event system will work in all sleep modes. One exception is software events which require a system clock.
Asynchronous event users are able to respond to an event without their clock running, i.e. in Standby Sleep mode. Synchronous event users require their clock to be running to be able to respond to events. Such users will only work in Idle Sleep mode or in Standby Sleep mode if configured to run in Standby mode by setting the RUNSTBY bit in the appropriate register.
Asynchronous event generators are able to generate an event without their clock running, i.e. in Standby Sleep mode. Synchronous event generators require their clock to be running to be able to generate events. Such generators will only work in Idle Sleep mode or in Standby Sleep mode if configured to run in Standby mode by setting the RUNSTBY bit in the appropriate register.