Light sleepers wake up easily due to little disturbances like noise, light, or movement. Being a light sleeper isn't just a nuisance, it can affect your sleep cycles and lead to poor sleep quality.

Our sleep-wake cycle is governed by the circadian rhythm, the body’s internal clock that tells us when to sleep, wake, eat, and work. At 8 a.m., your cortisol levels spike, helping you feel awake.

During the height of the Cold War movie makers feasted on the concept of "sleepers", supposedly everyday Americans programmed to react to directions from their Soviet masters at a time of need.