diff --git a/01.js b/01.js
index 03a2a3f..078c846 100644
--- a/01.js
+++ b/01.js
@@ -36,25 +36,37 @@ addObjects();
 gameLoop();
 
 function setupMatter() {
-  engine = Matter.Engine.create();
+  engine = Matter.Engine.create({ enableSleeping: true });
 }
 
 function addObjects() {
   boxes.push(
-    new Box(engine.world, 250, 20, 40, 40),
-    new Box(engine.world, 300, 350, 40, 40),
-    new Box(engine.world, 320, 70, 40, 40),
-    new Box(engine.world, 0, 400, 800, 60, { isStatic: true })
+    new Box(engine.world, 250, 20, 40, 40, { restitution: 0.8 }),
+    new Box(engine.world, 300, 350, 40, 40, { restitution: 0.8 }),
+    new Box(engine.world, 320, 70, 40, 40, { restitution: 0.8 }),
+    new Box(engine.world, 0, 400, 1200, 60, { isStatic: true }),
+    new Box(engine.world, 260, 50, 40, 40),
+    new Box(engine.world, 330, 300, 40, 40),
+    new Box(engine.world, 350, 170, 40, 40),
+    new Box(engine.world, 160, 150, 40, 40),
+    new Box(engine.world, 190, 300, 40, 40),
+    new Box(engine.world, 250, 270, 40, 40),
   );
 }
 
 function gameLoop() {
   // update the physics world
   Matter.Engine.update(engine, 1000 / 60);
+var sleepingCount = 0;
   // update the DOM world
   for (let b of boxes) {
     b.update();
+if (b.physicsBox.isSleeping)
+{
+    sleepingCount += 1;
+}
   }
+console.debug("sleeping count:", sleepingCount);
   requestAnimationFrame(() => this.gameLoop());
 }
 
diff --git a/index.html b/index.html
index 4e35225..481224e 100644
--- a/index.html
+++ b/index.html
@@ -22,7 +22,7 @@ box {
   box-sizing: border-box;
   position: absolute;
   display: block;
-  background-color: rgba(45, 188, 232, 0.687);
+  background-color: red;
   transform-origin: 20px 20px;
 }