User Names as email

Hi (SugarCRM Pro v11, sugarcloud)

In order to make changes to our AD for singled sign on, my support has requested all user names are changed to the user email.

Can an email address be used as a user name and would this change have any adverse effect?

If it can be done, is there a quick way of updating the user names or will they all need to be changed manually?

Kind regards john