Sleep phone when not in motion

Hi,

I am building an app which runs on a smartphone attached to a rotating object. When the phone rotates, the gyro detects this and changes the image. However, to avoid overheating on the device I would like the app to "sleep" after 60 seconds of no motion.

I am using input.gyro to move the camera using this script I got from the forums, modified a little so it only rotates on y.

 using UnityEngine;
 using System.Collections;
 
 // Activate head tracking using the gyroscope
 public class GyroCamera : MonoBehaviour {
     public GameObject player; // First Person Controller parent node
     public GameObject head; // First Person Controller camera
 
     // The initials orientation
     private float initialOrientationX;
     private float initialOrientationY;
     private float initialOrientationZ;
 
     // Use this for initialization
     void Start () {
         // Activate the gyroscope
         Input.gyro.enabled = true;
 
         // Save the firsts values
         initialOrientationX = Input.gyro.rotationRateUnbiased.x;
         initialOrientationY = Input.gyro.rotationRateUnbiased.y;
         initialOrientationZ = -Input.gyro.rotationRateUnbiased.z;
     }
 
     // Update is called once per frame
     void Update () {
         // Rotate the player and head using the gyroscope rotation rate
         player.transform.Rotate (0, initialOrientationY -Input.gyro.rotationRateUnbiased.y, 0);
         // head.transform.Rotate (initialOrientationX -Input.gyro.rotationRateUnbiased.x, 0, initialOrientationZ + Input.gyro.rotationRateUnbiased.z);
     }
 }

I am also using the following script attached to a empty gameobject to sleep:

 using UnityEngine;
 using System.Collections;
 
 public class sleeptimeout : MonoBehaviour {
     void Update() {
         Screen.sleepTimeout = 60;
     }
 }

however, the app never sleeps. Can anyone spot the problem?