creating a normal user just for reboot

Hi folks. I want to enable a user to login, and after succesful login the system reboots. I tried out the following: - creating an user - in ~/.profile I put "sudo /sbin/reboot" - with visudo I defined "<username> ALL: NOPASSWD: /sbin/reboot" but this won't work. Am I missing something or am I totally on the wrong way ? thx. Stephan