SET SERVEROUTPUT ON ;
BEGIN
    DBMS_OUTPUT.PUT_LINE('Start ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
    APEX_UTIL.PAUSE(5);
    DBMS_OUTPUT.PUT_LINE('End   ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
END;
/

CREATE OR REPLACE PROCEDURE SLEEP (P_MILLI_SECONDS IN NUMBER) 
AS LANGUAGE JAVA NAME 'java.lang.Thread.sleep(long)';
Note: Please remember, that “Thread.sleep” uses milli seconds!

Example – “Wait 5 seconds”:

SET SERVEROUTPUT ON ;
BEGIN
    DBMS_OUTPUT.PUT_LINE('Start ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
    SLEEP(5 * 1000);
    DBMS_OUTPUT.PUT_LINE('End   ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
END;
/

SET SERVEROUTPUT ON
BEGIN
  sys.DBMS_OUTPUT.put_line('Time 1: ' || TO_CHAR(SYSTIMESTAMP, 'HH24:MI:SS.FF'));

  -- Pause for 1 second.
  sys.DBMS_SESSION.sleep(1);

  sys.DBMS_OUTPUT.put_line('Time 2: ' || TO_CHAR(SYSTIMESTAMP, 'HH24:MI:SS.FF'));

  -- Pause for half a second.
  sys.DBMS_SESSION.sleep(0.5);

  sys.DBMS_OUTPUT.put_line('Time 3: ' || TO_CHAR(SYSTIMESTAMP, 'HH24:MI:SS.FF'));
END;
/
Time 1: 19:52:52.957473000
Time 2: 19:52:53.957187000
Time 3: 19:52:54.457213000

PL/SQL procedure successfully completed.

SQL>