diff --git a/_layouts/default.html b/_layouts/default.html
index e664522..12de50e 100644
--- a/_layouts/default.html
+++ b/_layouts/default.html
@@ -94,8 +94,9 @@
     <h2 class="project-tagline">{{ site.description | default: site.github.project_tagline }}</h2>
     <a href="/alertmanager" class="btn">Global configuration</a>
     <a href="/rules" class="btn">Rules</a>
-    <a href="https://github.com/samber/awesome-prometheus-alerts/blob/master/CONTRIBUTING.md" class="btn">Contribute on
-      GitHub
+    <a href="/sleep-peacefully" class="btn">Sleep peacefully</a>
+    <a href="https://github.com/samber/awesome-prometheus-alerts/blob/master/CONTRIBUTING.md" class="btn">
+      Contribute on GitHub
     </a>
 
     <ul class="github-buttons-cta">
diff --git a/index.md b/index.md
index 51bf367..4aef817 100644
--- a/index.md
+++ b/index.md
@@ -12,11 +12,15 @@
 
 
 <h2>
-  AlertManager configuration
+  Hello world
 </h2>
 
 <a href="/alertmanager">
-  See here
+  AlertManager configuration
+</a>
+
+<a href="/sleep-peacefully">
+  Alerting time window
 </a>
 
 <h2>
diff --git a/sleep-peacefully.md b/sleep-peacefully.md
new file mode 100644
index 0000000..1708f08
--- /dev/null
+++ b/sleep-peacefully.md
@@ -0,0 +1,87 @@
+<h1 style="text-align: center;">
+  Sleep Peacefully
+</h1>
+
+## Alerting time window
+
+In some applications, load and activity can vary over the day/week/year.
+
+In order to prevent alarm fatigue and busy pager, alerts can be disabled during a period of time (such as night or weekend).
+
+Example:
+
+- Weekday: `node_load5 > 10 and ON() (0 < day_of_week() < 6)`
+- Day time: `node_load5 > 10 and ON() (8 < hour() < 18)`
+- Exclude December: `node_load5 > 10 and ON() (month() != 12)`
+
+## Advanced time windows and timezones
+
+```yml
+# rules.yml
+
+- record: is_european_summer_time
+  expr: |
+      (vector(1) and (month() > 3 and month() < 10))
+      or
+      (vector(1) and (month() == 3 and (day_of_month() - day_of_week()) >= 25) and absent((day_of_month() >= 25) and (day_of_week() == 0)))
+      or
+      (vector(1) and (month() == 10 and (day_of_month() - day_of_week()) < 25) and absent((day_of_month() >= 25) and (day_of_week() == 0)))
+      or
+      (vector(1) and ((month() == 10 and hour() < 1) or (month() == 3 and hour() > 0)) and ((day_of_month() >= 25) and (day_of_week() == 0)))
+      or
+      vector(0)
+
+- record: europe_london_time
+  expr: time() + 3600 * is_european_summer_time
+- record: europe_paris_time
+  expr: time() + 3600 * (1 + is_european_summer_time)
+
+- record: europe_london_hour
+  expr: hour(europe_london_time)
+- record: europe_paris_hour
+  expr: hour(europe_paris_time)
+
+- record: europe_london_weekday
+  expr: 0 < day_of_week(europe_london_time) < 6
+- record: europe_paris_weekday
+  expr: 0 < day_of_week(europe_paris_time) < 6
+
+- record: europe_london_daytime
+  expr: 8 < europe_london_hour < 18
+- record: europe_paris_daytime
+  expr: 8 < europe_paris_hour < 18
+
+# new year's day / xmas / labor day / all saints' day / ...
+- record: europe_french_public_holidays
+  expr: |
+      (vector(1) and month(europe_paris_time) == 1 and day_of_month(europe_paris_time) == 1)
+      or
+      (vector(1) and month(europe_paris_time) == 12 and day_of_month(europe_paris_time) == 25)
+      or
+      (vector(1) and month(europe_paris_time) == 5 and day_of_month(europe_paris_time) == 1)
+      or
+      (vector(1) and month(europe_paris_time) == 11 and day_of_month(europe_paris_time) == 1)
+      or
+      vector(0)
+```
+
+```yml
+# alerts.yml
+
+- alert: HighLoadQuietDuringWeekendAndNight
+  expr: node_load5 > 10 and ON() (europe_london_weekday and europe_paris_weekday)
+
+- alert: HighLoadQuietDuringBackup
+  expr: node_load5 > 10 and ON() absent(hour() == 2)
+
+- alert: HighLoad
+  expr: |
+      node_load5 > 20 and ON() (europe_london_weekday and europe_paris_weekday)
+      or
+      node_load5 > 10
+```
+
+## Sources
+
+- [https://medium.com/@tom.fawcett/time-of-day-based-notifications-with-prometheus-and-alertmanager-1bf7a23b7695](https://medium.com/@tom.fawcett/time-of-day-based-notifications-with-prometheus-and-alertmanager-1bf7a23b7695)
+- [https://promcon.io/2019-munich/slides/improved-alerting-with-prometheus-and-alertmanager.pdf](https://promcon.io/2019-munich/slides/improved-alerting-with-prometheus-and-alertmanager.pdf)