Do you want to do your own small thing for the environment? Well you can start by saving on power when your computer is not in use. Yep, you can always set a timer or put it into sleep mode like lets say being idle for about 15 minutes or more. There is no sense in keeping your monitor live if you are not using your computer since other than being a waste of energy, you are probably adding some stress to the monitor as well.
Monitors have their own share of product life cycles. They have a specific number of useful years and if you are not careful, you may find yourself getting a new one unscheduled.
To some, there are issues. One of which is that of crash problems for computers that cannot hold the proper programming or hardware that is usually something that is common especially if you are using a chop-chop computer. In fact, some PCs may not even boot after they have been placed on sleep mode, most of which is due to some issues as far as load and processes are concerned.
Regardless, saving on power is something that is really the main issue for placing a computer in sleep mode. Some may not want to be interrupted but if you are perhaps at home and choose not to turn off your computer, putting it into sleep mode is a good alternative to that.