For many, the sensation of slipping into sleep can feel as if they’re falling into a void. This common experience, often described as “falling asleep,” may be more literal than previously thought.
The phrase “falling asleep” is well known, but beyond merely describing the irresistible pull into slumber, it captures a physical sensation that occurs at the threshold of sleep. During this initial stage of sleep, known as hypnagogia, some people actually feel as though they’re plummeting through space.
Muscle relaxation characterizes the first moments of sleep. However, this relaxation is sometimes interrupted by a sudden jerk or contraction of the muscles, known scientifically as a myoclonic jerk or more colloquially as a sleep start. This abrupt motion could involve the entire body or just specific parts like the legs or arms, leading to a brief awakening.
This unexpected body jerk can be accompanied by a strange sensation that might extend to what experts call a somesthetic hallucination—real physical and sensory sensations that lead to the feeling of falling. It’s not an isolated occurrence; studies suggest 60% to 70% of people experience this phenomenon at least once in their lives.
The precise cause remains a mystery. However, one theory suggests it’s due to the brain misinterpreting the body’s transition into sleep as a momentary lapse in muscle control. In response, the brain sends out signals to ensure everything is functioning correctly, which can result in the familiar feeling of falling or a sudden jolt awake.
Understanding this mechanism could help demystify an experience shared by millions, transforming a nighttime nuisance into a fascinating insight into our sleep behaviors.
