 In addition, the technique has been used clinically with patients who suffer from delayed sleep phase syndrome, helping them to awaken earlier in gradual steps, as the simulated dawn is moved earlier.A dawn simulator can be used as an alarm clock.Light enters through the eyelids triggering the body to begin its wake-up cycle, including the release of cortisol, so that by the time the light is at full brightness, sleepers wake up on their own, without the need for an alarm.