Can I Sleep/Wake a networked computer?

I'm building an automated backup system around Macrium Reflect Pro. Ideally, I'd like to put all the computers to sleep around 8:00 PM then wake them around 1:00 AM and run the backups. Problem is, how do I put the networked computer to sleep, then wake it, run the backup and put it back to sleep? Also, I sometimes get system updates from MS in the middle of the night. If my backup is...