automatic update = unhappy users

For the users who do not have administrator’s right, the Windows Update is set to download and installed automatically at 3am (default) everyday. When they return in the morning and boot the computer, Windows will prompt them to restart the computer if an update has been installed. For some, the message came up when the users are away from the desk and the computer restart itself after 15 seconds. As a result, some of their unsaved work are lost and they are not happy about it. Is there way to overcome this issue? Since they’re allowed to manually install those updates, they have no control over when to restart the pc. Please advise.

Thanks.