diff --git a/polyglot.ini b/polyglot.ini
index 4e825f3c..cd7a3188 100644
--- a/polyglot.ini
+++ b/polyglot.ini
@@ -31,7 +31,6 @@ Aggressiveness = 100
 Cowardice = 100
 Min Split Depth = 0
 Threads = 1
-Idle Threads Sleep = true
 Hash = 128
 Ponder = true
 OwnBook = false
diff --git a/src/search.cpp b/src/search.cpp
index 22a954ae..dfe690b4 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -226,14 +226,12 @@ void Search::think() {
   for (size_t i = 0; i < Threads.size(); ++i)
       Threads[i]->maxPly = 0;
 
-  Threads.sleepWhileIdle = Options["Idle Threads Sleep"];
   Threads.timer->run = true;
   Threads.timer->notify_one(); // Wake up the recurring timer
 
   id_loop(RootPos); // Let's start searching !
 
   Threads.timer->run = false; // Stop the timer
-  Threads.sleepWhileIdle = true; // Send idle threads to sleep
 
   if (Options["Write Search Log"])
   {
@@ -1462,7 +1460,7 @@ void Thread::idle_loop() {
   {
       // If we are not searching, wait for a condition to be signaled instead of
       // wasting CPU time polling for work.
-      while ((!searching && Threads.sleepWhileIdle) || exit)
+      while (!searching || exit)
       {
           if (exit)
           {
@@ -1537,8 +1535,7 @@ void Thread::idle_loop() {
 
           // Wake up the master thread so to allow it to return from the idle
           // loop in case we are the last slave of the split point.
-          if (    Threads.sleepWhileIdle
-              &&  this != sp->masterThread
+          if (    this != sp->masterThread
               &&  sp->slavesMask.none())
           {
               assert(!sp->masterThread->searching);
diff --git a/src/thread.cpp b/src/thread.cpp
index 06244dc9..344cfb79 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -181,13 +181,12 @@ void MainThread::idle_loop() {
 
 
 // init() is called at startup to create and launch requested threads, that will
-// go immediately to sleep due to 'sleepWhileIdle' set to true. We cannot use
-// a c'tor because Threads is a static object and we need a fully initialized
-// engine at this point due to allocation of Endgames in Thread c'tor.
+// go immediately to sleep. We cannot use a c'tor because Threads is a static
+// object and we need a fully initialized engine at this point due to allocation
+// of Endgames in Thread c'tor.
 
 void ThreadPool::init() {
 
-  sleepWhileIdle = true;
   timer = new_thread<TimerThread>();
   push_back(new_thread<MainThread>());
   read_uci_options();
diff --git a/src/thread.h b/src/thread.h
index 66df55b5..35654312 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -166,7 +166,6 @@ struct ThreadPool : public std::vector<Thread*> {
   void wait_for_think_finished();
   void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
 
-  bool sleepWhileIdle;
   Depth minimumSplitDepth;
   Mutex mutex;
   ConditionVariable sleepCondition;
diff --git a/src/ucioption.cpp b/src/ucioption.cpp
index e117e44c..d5db2c97 100644
--- a/src/ucioption.cpp
+++ b/src/ucioption.cpp
@@ -71,7 +71,6 @@ void init(OptionsMap& o) {
   o["Cowardice"]                << Option(100, 0, 200, on_eval);
   o["Min Split Depth"]          << Option(0, 0, 12, on_threads);
   o["Threads"]                  << Option(1, 1, MAX_THREADS, on_threads);
-  o["Idle Threads Sleep"]       << Option(true);
   o["Hash"]                     << Option(32, 1, 16384, on_hash_size);
   o["Clear Hash"]               << Option(on_clear_hash);
   o["Ponder"]                   << Option(true);