diff --git a/growpi.toml b/growpi.toml
index 2c6816a..687c687 100644
--- a/growpi.toml
+++ b/growpi.toml
@@ -34,6 +34,7 @@ temperature_set_point_upper = 35.0
 temperature_set_point_lower = 28.0
 temperature_loop_mins = 60
 sunlight_hours = 24
+lights_off_hour = 0
 watering_frequency_hours = 30
 watering_amount_grams = 200
 
diff --git a/src/config.rs b/src/config.rs
index 094bf3d..6649440 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -50,6 +50,7 @@ pub struct ControllerSettings {
     pub temperature_set_point_lower: f32,
     pub temperature_loop_mins: u64,
     pub sunlight_hours: u64,
+    pub lights_off_hour: u64,
     pub watering_frequency_hours: u64,
     pub watering_amount_grams: u64,
 }
@@ -126,6 +127,7 @@ impl Default for Configuration {
                 sunlight_hours: 24,
                 watering_frequency_hours: 30,
                 watering_amount_grams: 200,
+                lights_off_hour: 0,
             },
             data_logging_settings: DataLoggingSettings {
                 enabled: true,
diff --git a/src/control/light.rs b/src/control/light.rs
index 4bba31c..92c153a 100644
--- a/src/control/light.rs
+++ b/src/control/light.rs
@@ -8,12 +8,22 @@ use crate::{
     state::{lock_state, ProgramStateShared},
 };
 
+fn should_turn_on_light(on_hours: u64, lights_out: u64, current_hour: u64) -> bool {
+    let off_hours = 24 - on_hours;
+    (lights_out..(lights_out + off_hours))
+        .map(|x| x % 24)
+        .any(|x| x == current_hour)
+}
+
 fn light_control(program_state: ProgramStateShared) -> GenericResult<()> {
     let program_state = program_state.clone();
     let mut program_state = lock_state(&program_state)?;
-    let local = Local::now();
-    let hour = local.time().hour();
-    if hour as u64 <= program_state.config.controller_settings.sunlight_hours {
+
+    let on_hours = program_state.config.controller_settings.sunlight_hours;
+    let current_hour = Local::now().time().hour() as u64;
+    let lights_out_hour = program_state.config.controller_settings.lights_off_hour;
+
+    if should_turn_on_light(on_hours, lights_out_hour, current_hour) {
         actuators::switch_lights(crate::io::RelaySwitchState::On, &mut program_state)?;
     } else {
         actuators::switch_lights(crate::io::RelaySwitchState::Off, &mut program_state)?;
@@ -28,3 +38,31 @@ pub async fn light_control_loop(program_state: ProgramStateShared) {
         tokio::time::sleep(Duration::from_hours(1)).await;
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_should_turn_on_light() {
+        assert!(!should_turn_on_light(24, 5, 4));
+        assert!(!should_turn_on_light(24, 5, 5));
+        assert!(!should_turn_on_light(24, 5, 6));
+        assert!(!should_turn_on_light(24, 0, 0));
+        assert!(!should_turn_on_light(24, 0, 23));
+        assert!(!should_turn_on_light(24, 0, 1));
+
+        assert!(!should_turn_on_light(23, 5, 4));
+        assert!(should_turn_on_light(23, 5, 5));
+        assert!(!should_turn_on_light(23, 5, 6));
+        assert!(!should_turn_on_light(23, 0, 23));
+        assert!(should_turn_on_light(23, 0, 0));
+        assert!(!should_turn_on_light(23, 0, 1));
+
+        assert!(!should_turn_on_light(20, 22, 21));
+        assert!(should_turn_on_light(20, 22, 22));
+        assert!(should_turn_on_light(20, 22, 23));
+        assert!(should_turn_on_light(20, 22, 0));
+        assert!(should_turn_on_light(20, 22, 1));
+        assert!(!should_turn_on_light(20, 22, 2));
+    }
+}