Login session cookie expiration

Hi.
I’d like to have the user login session expire lets say 1 hour (or less) after every login, so that each user must login again next time. This is to make sure no user is logged in long after leaving just because they forgot to hit logout.
Is there a way to do this? If not, does anyone have a better idea to have users logged out automatically even if they forget to do it themselves?
Just wanna make the login/logout process as simple as possible for the users, and what can be more simple than not having to think about logout at all? 🙂