diff --git a/doc/applied/heart_beat b/doc/applied/heart_beat
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+SYNOPSIS
+        void heart_beat()
+
+DESCRIPTION
+        This function will be called automatically every
+        __HEART_BEAT_INTERVAL__ seconds. The driver will call the function
+        directly in the object, even if the function is being shadowed.
+
+        The start and stop of heart beat is controlled by the efun
+        set_heart_beat(). Be careful not to have objects with heart
+        beat running all the time, as it uses a lot of driver
+        resources. If there is an error in the heart beat routine, the
+        heart beat will be turned off for this object and the
+        master function heart_beat_error() is called. If the call
+        to the master function returns a non-zero value, the heart beat
+        will be turned back on again.
+
+        The function this_player() will return this object, but only if
+        it is living. Otherwise, this_player() will return 0.
+
+        The function will be called only if there is at least one interactive
+        user in the game.
+
+        Note that error messages will be given to the current user
+        which will be the object itself or nobody.
+
+EXAMPLE
+        object owner;
+        void create() {
+           ...
+           owner=this_player();
+           set_heart_beat(1);
+        }
+        void heart_beat() {
+           tell_object(owner, "Your heart goes: BUM BUM\n");
+        }
+
+        We have to use tell_object() because write goes to the current
+        user and this can only be the object itself or nobody.
+
+HISTORY
+        LDMud 3.3.687 made the interval time configurable at driver compile
+        time (used to be 2 seconds fixed).
+
+SEE ALSO
+        set_heart_beat(E), call_out(E), enable_commands(E),
+        heart_beat_error(M)