Have you ever been drifting off to sleep when suddenly your body twitches, almost like you’re falling? That’s called a hypnic jerk , also known as a sleep start. According to the National Sleep Foundation, up to 70% of people experience hypnic jerks occasionally , while about 10% experience them regularly enough to disrupt sleep . Factors like lack of sleep, stress, caffeine, and poor posture play a major role. Surprisingly, even the wrong sleep pillow can worsen the problem. But don’t worry—hypnic jerks are usually harmless and preventable with the right lifestyle adjustments. Let’s break down everything you need to know about this quirky sleep phenomenon. What is a Hypnic Jerk? A hypnic jerk is an involuntary muscle twitch that occurs during the transition from wakefulness to sleep. It feels like your body is jerking suddenly, often accompanied by the sensation of falling. Scientists describe it as a type of myoclonus —a brief, involuntary muscle movement. While startling, hyp...