cast time interval to seconds - Mailing list pgsql-general

Hi, I have two columns start_time & stop_time declared as "TIME". I'd
like to compute the difference between the two times in seconds, all in db:

SELECT
   (CAST(stop_time AS SECONDS) + 86400 - CAST(start_time AS SECONDS))
   % 86400;

Unfortunately AS SECONDS causes parse error. Any hints? Thanks.