diff --git a/src/platform/esp32.rs b/src/platform/esp32.rs
index f25e270..b952ea8 100644
--- a/src/platform/esp32.rs
+++ b/src/platform/esp32.rs
@@ -4,6 +4,7 @@ use std::fmt::Debug;
 use std::sync::Mutex;
 
 use chrono::DateTime;
+use chrono::Timelike;
 use chrono::Utc;
 
 use esp_idf_svc::eventloop::{EspSubscription, EspSystemEventLoop, System};
@@ -203,11 +204,95 @@ impl Board for Esp32Board {
         let nvs = EspDefaultNvsPartition::take().unwrap();
         FixedSizeScheduler::new([
             Box::new(WifiTask::new(self.modem.take().unwrap(), self.sys_loop.clone(), &nvs)),
+            Box::new(CircadianRhythm::new()),
             Box::new(self.surfaces.clone())
         ])
     }
 }
 
+#[derive(Debug, Clone, Copy)]
+struct ScheduleEntry {
+    hour: u8,
+    brightness: u8
+}
+
+struct CircadianRhythm {
+    time_check: Periodically,
+    schedule: [ScheduleEntry;10]
+}
+
+impl CircadianRhythm {
+    fn new() -> Self {
+        CircadianRhythm {
+            time_check: Periodically::new_every_n_seconds(5),
+            schedule: [
+                ScheduleEntry { hour: 0, brightness: 0 },
+                ScheduleEntry { hour: 5, brightness: 0 },
+                ScheduleEntry { hour: 6, brightness: 10 },
+                ScheduleEntry { hour: 7, brightness: 20 },
+                ScheduleEntry { hour: 8, brightness: 80 },
+                ScheduleEntry { hour: 11, brightness: 120 },
+                ScheduleEntry { hour: 18, brightness: 200 },
+                ScheduleEntry { hour: 19, brightness: 255 },
+                ScheduleEntry { hour: 22, brightness: 120 },
+                ScheduleEntry { hour: 23, brightness: 5 }
+            ]
+        }
+    }
+
+    fn brightness_for_time(&self, hour: u8, minute: u8) -> u8 {
+        let mut start = self.schedule.last().unwrap();
+        let mut end = self.schedule.first().unwrap();
+        for cur in self.schedule.iter() {
+            if (cur.hour <= hour ) {
+                start = cur;
+            } else {
+                end = cur;
+                break;
+            }
+        }
+
+        log::info!("hour={:?} minute={:?} start={:?} end={:?}", hour, minute, start, end);
+
+        let mut adjusted_end = end.clone();
+        if start.hour > end.hour {
+            adjusted_end.hour += 24;
+        }
+
+        let start_time = start.hour * 60;
+        let end_time = end.hour * 60;
+        let now_time = hour * 60 + minute;
+
+        let duration = end_time - start_time;
+        let cur_duration = now_time - start_time;
+
+        let frac = map_range(cur_duration.into(), 0, duration.into(), 0, 255) as u8;
+
+        lerp8by8(start.brightness, end.brightness, frac)
+    }
+}
+
+fn map_range(x: u16, in_min: u16, in_max: u16, out_min: u16, out_max: u16) -> u16 {
+    let run = in_max - in_min;
+    if run == 0 {
+        return 0;
+    }
+    let rise = out_max - out_min;
+    let delta = x - in_min;
+    return (delta * rise) / run + out_min;
+}
+
+
+impl Task for CircadianRhythm {
+    fn tick(&mut self, event: &Event, bus: &mut EventBus) {
+        if self.time_check.tick() || event.eq(&Event::ReadyToRock) {
+            let now: DateTime<Utc> = std::time::SystemTime::now().into();
+            let next_brightness = self.brightness_for_time(now.hour() as u8, now.minute() as u8);
+            bus.push(Event::new_property_change("output.brightness", next_brightness));
+        }
+    }
+}
+
 impl Debug for WifiTask {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("WifiTask").finish()