diff --git a/journal/2021-08-30.md b/journal/2021-08-30.md
index 7e044d8bf..a173e7b86 100644
--- a/journal/2021-08-30.md
+++ b/journal/2021-08-30.md
@@ -8,4 +8,5 @@
   - [[the road to reality]]
     - by [[roger penrose]]
   - [[one, two, three... infinity]]
-    - by [[george gamow]]
\ No newline at end of file
+    - by [[george gamow]]
+- [[sleeping beauty problem]]
\ No newline at end of file
diff --git a/sleeping beauty problem.md b/sleeping beauty problem.md
new file mode 100644
index 000000000..23565177d
--- /dev/null
+++ b/sleeping beauty problem.md	
@@ -0,0 +1,4 @@
+# sleeping beauty problem
+
+- [[wp]] https://en.wikipedia.org/wiki/Sleeping_Beauty_problem
+