diff --git a/skiplang/prelude/runtime/runtime32_specific.c b/skiplang/prelude/runtime/runtime32_specific.c
index 8057ec060..8e7654b7a 100644
--- a/skiplang/prelude/runtime/runtime32_specific.c
+++ b/skiplang/prelude/runtime/runtime32_specific.c
@@ -158,6 +158,16 @@ uint64_t SKIP_time_ms() {
   return (((uint64_t)hi) << 32) | ((uint64_t)lo);
 }
 
+uint64_t SKIP_time_ns() {
+  // No nanosecond precision on 32-bit/WASM; fall back to milliseconds * 1e6.
+  return SKIP_time_ms() * 1000000;
+}
+
+void SKIP_sleep_ms(uint64_t ms) {
+  // Not implemented on 32-bit/WASM.
+  (void)ms;
+}
+
 void SKIP_flush_stdout() {
   // Not implemented
 }
diff --git a/skiplang/prelude/runtime/runtime64_specific.cpp b/skiplang/prelude/runtime/runtime64_specific.cpp
index c1a0ef697..8be18e416 100644
--- a/skiplang/prelude/runtime/runtime64_specific.cpp
+++ b/skiplang/prelude/runtime/runtime64_specific.cpp
@@ -32,6 +32,7 @@ extern "C" {
 #include <map>
 #include <random>
 #include <string>
+#include <thread>
 #include <vector>
 
 extern "C" {
@@ -442,6 +443,17 @@ uint64_t SKIP_time_ms() {
       .count();
 }
 
+uint64_t SKIP_time_ns() {
+  using namespace std::chrono;
+
+  return duration_cast<nanoseconds>(steady_clock::now().time_since_epoch())
+      .count();
+}
+
+void SKIP_sleep_ms(uint64_t ms) {
+  std::this_thread::sleep_for(std::chrono::milliseconds(ms));
+}
+
 char* SKIP_unix_strftime(char* formatp, char* timep) {
   struct tm* tm = (struct tm*)timep;
   char buffer[1024];
diff --git a/skiplang/prelude/src/stdlib/other/Time.sk b/skiplang/prelude/src/stdlib/other/Time.sk
index ca9362066..e546ea8f7 100644
--- a/skiplang/prelude/src/stdlib/other/Time.sk
+++ b/skiplang/prelude/src/stdlib/other/Time.sk
@@ -10,6 +10,17 @@ native fun time(): Int;
 @cpp_extern("SKIP_time_ms")
 native fun time_ms(): Int;
 
+// Current time in nanoseconds from a monotonic clock (steady_clock).
+// Suitable for measuring elapsed time, not wall-clock time.
+@debug
+@cpp_extern("SKIP_time_ns")
+native fun time_ns(): Int;
+
+// Sleep for the given number of milliseconds.
+@debug
+@cpp_extern("SKIP_sleep_ms")
+native fun sleep_ms(ms: Int): void;
+
 @cpp_extern("SKIP_strftime")
 native fun strftime(format: String, timestamp: Int): String;
 
diff --git a/skiplang/prelude/tests/skfs/TestRuntime.sk b/skiplang/prelude/tests/skfs/TestRuntime.sk
index a69867271..e047a405f 100644
--- a/skiplang/prelude/tests/skfs/TestRuntime.sk
+++ b/skiplang/prelude/tests/skfs/TestRuntime.sk
@@ -151,4 +151,22 @@ fun testRuntime(): void {
   );
 }
 
+@test
+fun testTimeNs(): void {
+  t1 = Time.time_ns();
+  SKTest.expectTrue(t1 > 0, "time_ns: returns positive value");
+  t2 = Time.time_ns();
+  SKTest.expectTrue(t2 >= t1, "time_ns: monotonically non-decreasing");
+}
+
+@test
+fun testSleepMs(): void {
+  before = Time.time_ns();
+  Time.sleep_ms(1);
+  after = Time.time_ns();
+  elapsed = after - before;
+  SKTest.expectTrue(elapsed > 1000000, "sleep_ms: slept at least 1ms");
+  SKTest.expectTrue(elapsed < 10000000, "sleep_ms: slept less than 10ms");
+}
+
 module end;