PGsql function timestamp issue

create or replace function dw.fx_nish()
returns text
  language plpgsql
  as
$$
declare
x timestamp with time zone;
y timestamp with time zone;
begin
x:= current_timestamp;
perform pg_sleep(5);
y:= current_timestamp;
if x=y then
return 'SAME';
else
return 'DIFFERENT';
end if;

end;
$$