There may be cases where you want to prevent your computer from going to sleep after a period of inactivity.
Common reasons may be to prevent data loss on various business applications or to have the computer available for remote access after hours.
You can still allow the screen to power down if you need to to save power and prolong the live of the screen.
Windows 7, 8 & 10
Click your start button and type 'power'
Select 'Power options' from the search results
Click 'Change Plan Options' and adjust the sleep option to 'Never'
Save changes and you're done!