diff --git src/monster/melee2.c src/monster/melee2.c
index 2c34346..22be616 100644
--- src/monster/melee2.c
+++ src/monster/melee2.c
@@ -2782,6 +2782,8 @@ static void process_monster(struct cave *c, int m_idx)
 	monster_type *m_ptr = cave_monster(cave, m_idx);
 	monster_race *r_ptr = &r_info[m_ptr->r_idx];
 	monster_lore *l_ptr = &l_list[m_ptr->r_idx];
+	monster_type *m_nb_ptr;
+	monster_lore *l_nb_ptr;
 
 	int i, d, oy, ox, ny, nx;
 
@@ -2998,6 +3000,33 @@ static void process_monster(struct cave *c, int m_idx)
 		}
 	}
 
+	/* Try to wake up neighboring monsters in 50% probability */
+#if 1
+	if (!rf_has(r_ptr->flags, RF_STUPID) && randint0(2))
+	{
+		int k, y, x, wakeup;
+		for (k = 0, y = oy - 1; y <= oy + 1; y++)
+			for (x = ox - 1; x <= ox + 1; x++)
+			{
+				if (y == oy && x == ox) continue;
+				if (cave->m_idx[y][x] > 0)
+				{
+					m_nb_ptr = cave_monster(cave, cave->m_idx[y][x]);
+					l_nb_ptr = &l_list[m_nb_ptr->r_idx];
+					if ((wakeup = m_nb_ptr->m_timed[MON_TMD_SLEEP]) > 1)
+					{
+						wakeup -= 1;
+						/* Cap at 200 */
+						if (wakeup > 200) { wakeup = 200; }
+						mon_dec_timed(m_nb_ptr, MON_TMD_SLEEP, wakeup , MON_TMD_FLG_NOMESSAGE, FALSE);
+						k++;
+					}
+				}
+			}
+			if (k) return;
+	}
+#endif
+
 	/* Normal movement */
 	if (!stagger)
 		/* Logical moves, may do nothing */