diff --git a/src/fluxAccessory.ts b/src/fluxAccessory.ts
index 899e904..fb988e8 100644
--- a/src/fluxAccessory.ts
+++ b/src/fluxAccessory.ts
@@ -11,6 +11,7 @@ import HueError = require("node-hue-api/lib/HueError");
 let Service: HAPNodeJS.Service;
 let Characteristic: HAPNodeJS.Characteristic;
 const SECONDS_IN_DAY = 86400000;
+const MINUTES_IN_MILLISECOND = 60000;
 const SECONDS_IN_HOUR = 3600;
 
 export interface IFluxProps {
@@ -53,8 +54,6 @@ export class FluxAccessory implements IAccessory {
 
         this._times = getTimes(new Date(), this._config.latitude, this._config.longitude);
 
-        this.getLights();
-
         this.platformAccessory = new this._homebridge.platformAccessory(this.name, this.generateUUID(), this._homebridge.hap.Accessory.Categories.SWITCH);
 
         //@ts-ignore
@@ -192,6 +191,28 @@ export class FluxAccessory implements IAccessory {
         });
     }
 
+    /**
+     * Gets adjusted color temperature.
+    */
+    private getTempOffset = (startTemp: number, endTemp: number, startTime: Date, endTime: Date) => {
+        const now = this.getNow().getTime()
+        const percentComplete = ((now - startTime.getTime()) / (endTime.getTime() - startTime.getTime()));
+        const tempRange = Math.abs(startTemp - endTemp);
+        const tempOffset = tempRange * percentComplete
+        return startTemp - tempOffset;
+    }
+
+    /**
+     * Get the current time. Use test time if present.
+     */
+    private getNow() {
+        if (this._config.testNowDateString) {
+            return new Date(this._config.testNowDateString);
+        } else {
+            return new Date();
+        }
+    }
+
     private update = async (): Promise<void> => {
         this._isActive = true;
         while (this._isActive) {
@@ -199,39 +220,28 @@ export class FluxAccessory implements IAccessory {
                 await this.getLights();
             }
 
-            const now = new Date(Date.now());
+            const now = this.getNow();
             //Pad start time by an hour before sunset
-            const start = new Date(this._times.sunset.getTime() - 3 * 1000 * SECONDS_IN_HOUR);
-            const end = new Date(this._times.sunrise.getTime() + 1 * SECONDS_IN_DAY);
-            // const sunset = new Date('Wed, 15 Apr 2020 21:00:00 GMT');
-            // const sunrise = new Date('Wed, 15 Apr 2020 23:00:00 GMT');
+            const start = new Date(this._times.sunset.getTime() - (30 * MINUTES_IN_MILLISECOND));
+            const sunsetStart = this._times.sunsetStart;
+            const sunsetEnd = new Date(this._times.sunset.getTime() + this._config.sunsetDuration);
+            const nightStart = new Date(sunsetEnd.getTime() + 30 * MINUTES_IN_MILLISECOND);
+            const sunrise = new Date(this._times.sunrise.getTime() + 1 * SECONDS_IN_DAY);
 
-            const startColorTemp = this._config.startColorTemp ? this._config.startColorTemp : 4000;
-            const stopColorTemp = this._config.stopColorTemp ? this._config.stopColorTemp : 1900;
+            const startColorTemp = this._config.ceilingColorTemp ? this._config.ceilingColorTemp : 4000;
+            const sunsetColorTemp = this._config.sunsetColorTemp ? this._config.sunsetColorTemp : 2800;
+            const floorColorTemp = this._config.floorColorTemp ? this._config.floorColorTemp : 1900;
 
-            let percentageComplete = 0;
             let newTemp = 0;
 
-            const midTime = (end.getTime() - start.getTime()) / 2;
-            const mid = new Date(new Date().setTime(start.getTime() + midTime));
-            const tempRange = Math.abs(startColorTemp - stopColorTemp);
-
-            if ((start < now) && (now < mid)) {
-                //Before sunset; calculate temp based on TOD
-                const totalDecreaseTime = (mid.getTime() - start.getTime()) / 1000;
-                const secondsFromStart = (now.getTime() - start.getTime()) / 1000;
-                percentageComplete = secondsFromStart / totalDecreaseTime;
-                const tempOffset = tempRange * percentageComplete;
-
-                newTemp = startColorTemp - tempOffset;
-            } else if ((mid < now) && (now < end)) {
-                //After sunset; calculate temp based on TOD
-                const totalIncreaseTime = (end.getTime() - mid.getTime()) / 1000;
-                const secondsUntilSunrise = (end.getTime() - now.getTime()) / 1000;
-                percentageComplete = secondsUntilSunrise / totalIncreaseTime;
-
-                const tempOffset = tempRange * percentageComplete;
-                newTemp = startColorTemp - tempOffset;
+            if ((start < now) && (now < sunsetStart)) {
+                newTemp = this.getTempOffset(startColorTemp, sunsetColorTemp, start, sunsetStart);
+            } else if ((sunsetStart < now) && (now < sunsetEnd)) {
+                newTemp = this._config.sunsetColorTemp;
+            } else if ((sunsetEnd < now) && (now < nightStart)) {
+                newTemp = this.getTempOffset(sunsetColorTemp, floorColorTemp, sunsetEnd, nightStart);
+            } else if ((nightStart < now) && (now < sunrise)) {
+                newTemp = this._config.floorColorTemp;
             }
 
             //Set lights
diff --git a/src/models/iConfig.ts b/src/models/iConfig.ts
index e4edae7..c9cd686 100644
--- a/src/models/iConfig.ts
+++ b/src/models/iConfig.ts
@@ -3,12 +3,59 @@ export interface IConfig {
     ipAddress: string;
     userName?: string;
     clientKey?: string;
+
+    /**
+     * Latitude
+     */
     latitude: number;
+
+    /**
+     * Longitute
+     */
     longitude: number;
+
+    /**
+     * The list of lights to affect
+     */
     lights: Array<string>;
+
+    /**
+     * The name of the enable switch in homekit
+     */
     name: string;
-    startColorTemp?: number;
-    stopColorTemp?: number;
+
+    /**
+     * The color temperature at the start of sunset transition
+     */
+    ceilingColorTemp: number;
+
+    /**
+     * The color temp during the night
+     */
+    floorColorTemp: number;
+
+    /**
+     * The color temp at sunet
+     */
+    sunsetColorTemp: number;
+
+    /**
+     * The time in milliseconds the lights should remain at sunset temperature.
+     */
+    sunsetDuration: number;
+
+    /**
+     * The number of milliseconds the lights take to transition
+     */
     transition?: number;
+
+    /**
+     * The number of milliseconds to wait btw updates
+     */
     delay?: number;
+
+    /**
+     * The current formatted date and time to use with testing
+     */
+    testNowDateString?: string;
 }
\ No newline at end of file