diff --git a/README.md b/README.md
index fb568547..d22cce9f 100644
--- a/README.md
+++ b/README.md
@@ -64,6 +64,28 @@ $webPush = new WebPush($apiKeys);
 $webPush->sendNotification($endpoint, null, null, true);
 ```
 
+### Time To Live
+Time To Live (TTL, in seconds) is how long a push message is retained by the push service (eg. Mozilla) in case the user browser 
+is not yet accessible (eg. is not connected). You may want to use a very long time for important notifications. The default TTL is 4 weeks. 
+However, if you send multiple nonessential notifications, set a TTL of 0: the push notification will be delivered only 
+if the user is currently connected. For other cases, you should use a minimum of one day if your users have multiple time 
+zones, and if you don't several hours will suffice.
+
+```php
+<?php
+
+use Minishlink\WebPush\WebPush;
+
+$webPush = new WebPush(); // default TTL is 4 weeks
+// send some important notifications...
+
+$webPush->setTTL(3600);
+// send some not so important notifications
+
+$webPush->setTTL(0);
+// send some trivial notifications
+```
+
 ### Changing the browser client
 By default, WebPush will use `MultiCurl`, allowing to send multiple notifications in parallel.
 You can change the client to any client extending `\Buzz\Client\AbstractClient`.
diff --git a/src/WebPush.php b/src/WebPush.php
index 69c38210..f7984794 100644
--- a/src/WebPush.php
+++ b/src/WebPush.php
@@ -33,21 +33,23 @@ class WebPush
         'GCM' => 'https://android.googleapis.com/gcm/send',
     );
 
+    /** @var int Time To Live of notifications */
+    private $TTL;
+
     /**
      * WebPush constructor.
      *
      * @param array               $apiKeys Some servers needs authentication. Provide your API keys here. (eg. array('GCM' => 'GCM_API_KEY'))
-     * @param int|null            $TTL     Time to live of notifications
+     * @param int|null            $TTL     Time To Live of notifications, default being 4 weeks.
      * @param int|null            $timeout Timeout of POST request
      * @param AbstractClient|null $client
      */
-    public function __construct(array $apiKeys = array(), $TTL = null, $timeout = null, AbstractClient $client = null)
+    public function __construct(array $apiKeys = array(), $TTL = 2419200, $timeout = 30, AbstractClient $client = null)
     {
         $this->apiKeys = $apiKeys;
         $this->TTL = $TTL;
 
         $client = isset($client) ? $client : new MultiCurl();
-        $timeout = isset($timeout) ? $timeout : 30;
         $client->setTimeout($timeout);
         $this->browser = new Browser($client);
     }
@@ -155,14 +157,11 @@ private function sendToStandardEndpoints(array $notifications)
     {
         $headers = array(
             'Content-Length' => 0,
+            'TTL' => $this->TTL,
         );
 
         $content = '';
 
-        if (isset($this->TTL)) {
-            $headers['TTL'] = $this->TTL;
-        }
-
         $responses = array();
         /** @var Notification $notification */
         foreach ($notifications as $notification) {
@@ -177,8 +176,11 @@ private function sendToGCMEndpoints(array $notifications)
         $maxBatchSubscriptionIds = 1000;
         $url = $this->urlByServerType['GCM'];
 
-        $headers['Authorization'] = 'key='.$this->apiKeys['GCM'];
-        $headers['Content-Type'] = 'application/json';
+        $headers = array(
+            'Authorization' => 'key='.$this->apiKeys['GCM'],
+            'Content-Type' => 'application/json',
+            'TTL' => $this->TTL,
+        );
 
         $subscriptionIds = array();
         /** @var Notification $notification */
@@ -254,4 +256,20 @@ public function setBrowser($browser)
     {
         $this->browser = $browser;
     }
+
+    /**
+     * @return int
+     */
+    public function getTTL()
+    {
+        return $this->TTL;
+    }
+
+    /**
+     * @param int $TTL
+     */
+    public function setTTL($TTL)
+    {
+        $this->TTL = $TTL;
+    }
 }