IEumerator not recognising when a bool has switched

I’m trying to make a system where enemies will only spawn at night time. My spawner has a bool passed into by the Day/Night cycle script but my CoRoutine isn’t recognising when that bool changes from false to true. This is my code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Spawner : MonoBehaviour {
    public GameObject[] enemies;
    public Vector3 spawnValues;
    public float spawnWait;
    public float spawnMostWait;
    public float spawnMinWait;
    public bool stop;

    Sun sun;
    int randEnemy;

    public int startWait;
	// Use this for initialization
	void Start () {
        sun = GameObject.Find("SunLightCycle").GetComponent<Sun>();
	// Update is called once per frame
	void Update () {
        spawnWait = Random.Range(spawnMinWait, spawnMostWait);

    IEnumerator waitSpawner()
        yield return new WaitForSeconds(startWait);
        while (sun.isNight())
            Vector3 spawnPosition = new Vector3(Random.Range(-spawnValues.x, spawnValues.x), 1, Random.Range(-spawnValues.z, spawnValues.z));

            Instantiate(enemies[0], spawnPosition + transform.TransformPoint(0, 0, 0), gameObject.transform.rotation);

            yield return new WaitForSeconds(spawnWait);

If I change my scene so it starts at night time they will spawn but when it changes from day to night they will not spawn, any ideas?

Your coroutine will only run while it is night, as the code in the while loop states. That’s why it stops running afterwards.

You probably want the loop to run while the game is running, but only spawn if it’s night.