A frequent question about computers is – should I leave my pc on at night?
or off ? 
With the widespread problem of ransomware devastating effected businesses and users, there is now a very compelling reason on why it should be turned off it off at night. When it is off, it is significantly less likely to be infected or hacked, (of course not impossible though) ***
If hackers or viruses can get inside a network, they can then begin their task of going after other uncompromised computers and do widespread damage. Hackers love to do their damage and dirty work when no one is around to see the warning signs of their hacking such virus, firewall notices, or even strange program crashes.
For a typical business user, before or after normal working hours a hacker can have up to 16 hours to attack a computer, and for a typical home computer- 15 hours such as during sleeping hours and time away at work.
Weekends and (especially) holiday weekends are even larger time blocks when no one is around to be aware or see what is going on. Recently, more users are reporting successful large-scale attacks that have been perpetrated during holiday weekends. During long periods like these, they can spend many days attacking, infecting and or downloading data from compromised computers without anyone to notice signs of their dirty business.
Of course, another nice added benefit of shutting down the computer, is the saving of electricity. Not only does the computer and monitor consume electricity, but heat as well, and thus air conditioning use will increase since computers can generate a fair amount of heat by themselves.
On the opposite side though, when a computer is left on it is less likely to have a hardware failure that often happens on a cold start power-on. Turning on the pc, also known as “the power cycle” is a common time for components, such as the power supply or even more precious, the motherboard, to fail. Many individuals also choose to leave their computer on for their automated backups to run, for technicians or others to work on it, or they may even wish to work on their computer themselves -remotely.
So, in summary,
Benefits to turn it off – Much, much less likely to be “hacked” or infected, less heat produced, lower electricity bill for computer power and cooling.
Benefits to leaving it on – Longer lasting computer system, automatic backups can be done, remote access availability.
So, when possible, put it to sleep, hibernate it or better, turn the pc’s off when done for the day or a long period of time. Disconnecting the internet or turning it off is even better, if that is available option.
*** This assumes a hacker is able to directly contact a pc, such as when are able to get past a firewall and remain inside a network, which includes control over another computer or device (inside the network) Normally there are firewalls protecting computers from direct attack.