Just say "Alexa trigger sleep". Will keep your ecobee3 in the sleep comfort setting till next scheduled transition. For new people make sure to register your Amazon echo and your ecobee3 before using these recipes.
Then
Set thermostat comfort profile until next transition
This Action will set the thermostat into a hold using the settings from the specified comfort profile. This comfort profile hold will remain in effect until the next next comfort profile transition in the program.
Discover more time saving integrations for Button widget and ecobee