This will require a user to log back in if they are inactive for more than 10 minutes. In order for this feature to be used you must have a last_request_at datetime column in your table for whatever model you are authenticating with.

#User.rb
 acts_as_authentic do |c|
    c.logged_in_timeout = 10.minutes # default is 10.minutes
  end
 
#UserSession.rb
class UserSession < Authlogic::Session::Base
    logout_on_timeout true # default if false
  end