diff --git a/2018/day4/day4.py b/2018/day4/day4.py
new file mode 100644
index 0000000..e6aded4
--- /dev/null
+++ b/2018/day4/day4.py
@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+import re
+from collections import defaultdict, Counter
+from pprint import pprint
+
+
+def main(inp):
+    # total minutes asleep per guard
+    guards = defaultdict(int)
+    # list of guards sleeping for each minute
+    minutes = defaultdict(lambda: defaultdict(int))
+    for l in sorted(inp):
+        minute = re.search(r":(\d+)", l).group(1)
+        if "#" in l:
+            current_id = re.search(r"#(\d+)", l).group(1)
+        elif "asleep" in l:
+            start = int(minute)
+        elif "wakes" in l:
+            end = int(minute)
+            guards[current_id] += end - start
+            for m in range(start, end):
+                minutes[m][current_id] += 1
+
+    # Find the guard that has the most minutes asleep. What minute does that guard spend asleep the most?
+    guard_id = max(guards.items(), key=lambda x: x[1])[0]
+    minute = max([(k, v[guard_id]) for k, v in minutes.items() if guard_id in v], key=lambda x: x[1])[0]
+    print("Part 1: ", int(guard_id) * minute)
+
+    # Of all guards, which guard is most frequently asleep on the same minute?
+    maxs = { m: max(minutes[m].items(), key=lambda x: x[1]) for m in minutes.keys()}
+    minute, rest = max(maxs.items(), key=lambda x: x[1][1])
+    id_, _ = rest
+    print("Part 2: ", int(id_) * minute)
+
+
+if __name__ == '__main__':
+    import sys
+    infile = sys.argv[1] if len(sys.argv) > 1 else "example.txt"
+    with open(infile) as inp:
+        main(inp.readlines())
+