diff --git a/lib/classes/task/Scheduler.php b/lib/classes/task/Scheduler.php
index 32513b2fe9..0c2c69538a 100644
--- a/lib/classes/task/Scheduler.php
+++ b/lib/classes/task/Scheduler.php
@@ -47,6 +47,18 @@ class task_Scheduler
 
         return $this;
     }
+    protected function sleep($nsec)
+    {
+        $nsec = (integer) $nsec;
+        if ($nsec < 0) {
+            throw new \InvalidArgumentException(sprintf("(%s) is not > 0"));
+        }
+
+        $end = microtime(true) + $nsec;
+        while (microtime(true) < $end) {
+            usleep(10000);
+        }
+    }
 
     /**
      * @throws Exception if scheduler is already running
@@ -106,7 +118,7 @@ class task_Scheduler
 
                         return;
                     } else {
-                        sleep(2);
+                        $this->sleep(2);
                     }
                 } else {
                     // locked
@@ -167,9 +179,7 @@ class task_Scheduler
                 if (! $connwaslost) {
                     $this->log(sprintf("Warning : abox connection lost, restarting in 10 min."));
                 }
-                for ($i = 0; $i < 60 * 10; $i ++) {
-                    sleep(1);
-                }
+                $this->sleep(60 * 10);
                 try {
                     $conn = $this->dependencyContainer['phraseanet.appbox']->get_connection();
                 } catch (ErrorException $e) {
@@ -362,7 +372,7 @@ class task_Scheduler
                                 );
 
                                 if (is_resource($taskPoll[$tkey]["process"])) {
-                                    sleep(2); // let the process lock and write it's pid
+                                    $this->sleep(2);
                                 }
 
                                 if (is_resource($taskPoll[$tkey]["process"]) && ($pid = $taskPoll[$tkey]['task']->getPID()) !== null) {
@@ -568,9 +578,7 @@ class task_Scheduler
                 }
             }
 
-            for ($i = 0; $i < $sleeptime; $i ++) {
-                sleep(1);
-            }
+            $this->sleep($sleeptime);
         }
 
         $sql = "UPDATE sitepreff SET schedstatus='stopped', schedpid='0'";
diff --git a/lib/classes/task/abstract.php b/lib/classes/task/abstract.php
index 365f9f1923..93ddae7954 100644
--- a/lib/classes/task/abstract.php
+++ b/lib/classes/task/abstract.php
@@ -544,13 +544,14 @@ abstract class task_abstract
         if ($this->running) {       // && $this->records_done == 0)
             $when_started = time() - $when_started;
             if ($when_started < $this->period) {
-                for ($t = $this->period - $when_started; $this->running && $t > 0; $t --) { // DON'T do sleep($this->period - $when_started) because it prevents ticks !
+                for ($t = $this->period - $when_started; $this->running && $t > 0; $t --) { 
+                    // DON'T do sleep($this->period - $when_started) because it prevents ticks !
                     $s = $this->getState();
                     if ($s == self::STATE_TOSTOP) {
                         $this->setState(self::STATE_STOPPED);
                         $this->running = FALSE;
                     } else {
-                        sleep(1);
+                        $this->sleep(1);
                     }
                 }
             }
@@ -570,8 +571,9 @@ abstract class task_abstract
             throw new \InvalidArgumentException(sprintf("(%s) is not > 0"));
         }
 
-        while ($this->running && $nsec -- > 0) {
-            sleep(1);
+        $end = microtime(true) + $nsec;
+        while ($this->running && microtime(true) < $end) {
+            usleep(10000);
         }
     }
 
diff --git a/lib/classes/task/appboxAbstract.php b/lib/classes/task/appboxAbstract.php
index 38cf9db296..fc79b69b15 100644
--- a/lib/classes/task/appboxAbstract.php
+++ b/lib/classes/task/appboxAbstract.php
@@ -34,10 +34,7 @@ abstract class task_appboxAbstract extends task_abstract
                 if ($this->getRunner() == self::RUNNER_SCHEDULER) {
                     $this->log(("Warning : abox connection lost, restarting in 10 min."));
 
-                    // DON'T do sleep(600) because it prevents ticks !
-                    for ($t = 60 * 10; $this->running && $t; $t --) {
-                        sleep(1);
-                    }
+                    $this->sleep(60 * 10);
                     // because connection is lost we cannot change status to 'torestart'
                     // anyway the current status 'running' with no pid
                     // will enforce the scheduler to restart the task
diff --git a/lib/classes/task/databoxAbstract.php b/lib/classes/task/databoxAbstract.php
index c8258fb6e0..c8eb02befd 100644
--- a/lib/classes/task/databoxAbstract.php
+++ b/lib/classes/task/databoxAbstract.php
@@ -38,10 +38,7 @@ abstract class task_databoxAbstract extends task_abstract
                 if ($this->getRunner() == self::RUNNER_SCHEDULER) {
                     $this->log("appbox connection lost, restarting in 10 min.", self::LOG_ERROR);
 
-                    // DON'T do sleep(600) because it prevents ticks !
-                    for ($t = 60 * 10; $this->running && $t; $t--) {
-                        sleep(1);
-                    }
+                    $this->sleep(60 * 10);
                     // because connection is lost we cannot change status to 'torestart'
                     // anyway the current status 'running' with no pid
                     // will enforce the scheduler to restart the task
diff --git a/lib/classes/task/period/cindexer.php b/lib/classes/task/period/cindexer.php
index 399000bd2c..716769ba6e 100644
--- a/lib/classes/task/period/cindexer.php
+++ b/lib/classes/task/period/cindexer.php
@@ -524,7 +524,7 @@ class task_period_cindexer extends task_abstract
                         socket_write($sock, 'Q', 1);
                         socket_write($sock, "\r\n", strlen("\r\n"));
                         for ($i = 0; $this->running && $i < 5; $i ++) {
-                            sleep(1);
+                            $this->sleep(1);
                         }
                         $qsent = 'Q';
                         $timetokill = time() + 10;
@@ -562,7 +562,7 @@ class task_period_cindexer extends task_abstract
                 }
             }
             for ($i = 0; $this->running && $i < 5; $i ++) {
-                sleep(1);
+                $this->sleep(1);
             }
         }
 
@@ -594,7 +594,7 @@ class task_period_cindexer extends task_abstract
             } else {
                 chdir(dirname(__FILE__));
                 pcntl_exec($cmd, $args);
-                sleep(2);
+                $this->sleep(2);
             }
         } else {
             // parent
@@ -617,7 +617,7 @@ class task_period_cindexer extends task_abstract
                 if ($this->getState() == self::STATE_TOSTOP) {
                     posix_kill($pid, ($sigsent = SIGINT));
                     $timetokill = time() + 10;
-                    sleep(2);
+                    $this->sleep(2);
                 }
 
                 $status = NULL;
@@ -641,7 +641,7 @@ class task_period_cindexer extends task_abstract
                         $this->log('Kill signal sent to Phrasea indexer');
                         posix_kill($pid, ($sigsent = SIGKILL));
                     }
-                    sleep(2);
+                    $this->sleep(2);
                 }
             } // while running
         }
@@ -650,7 +650,7 @@ class task_period_cindexer extends task_abstract
     private function run_with_exec($cmd, $args, $args_nopwd)
     {
         pcntl_exec($cmd, $args);
-        sleep(2);
+        $this->sleep(2);
     }
 
     /**