I have personaly used the SMSWakeUp a tool from 1E. Here is the URL if you are intersted.
SMSWakeUp protects your IT health with 100% successful patches and system updates. Deployments can fail because PCs have been switched off by their users; SMSWakeUp powers on all PCs which are asleep or shutdown, guaranteeing successful deployment.
Do let me know if its helpful to you.