Have you ever experienced the feeling of falling as you start to fall asleep? Sometimes you may wake up to this feeling. If so, don't worry. Many people have felt the same thing.
In fact, the muscle twitches(肌肉抽搐) in the arms, legs or other parts of the body are called hypnic jerk(入睡抽动) or sleep starts. And they are very common. Up to 70 percent of people experience them sometimes, Huffing to Post reported. But what causes it?
There are some theories(理论). Some scientists believe that the feeling of falling comes from the body relaxing itself, especially if the person is anxious or unable to get comfortable. As you' re going to sleep, your muscles become relaxed. But your brain stays awake. It misunderstands the relaxing of your muscles as a sign that you' re falling. The brain then jerks the body awake as if it's trying to protect you.
Other scientists believe that different phase(时期) of sleep might cause hypnic jerks. When we sleep, we experience two phases: non-rapid eye movement(NREM,非快速眼动睡眠期) and rapid eye, movement(REM,快速眼动睡眠期). During REM, our heart rate can act irregularly. If the body experiences flashes(一瞬间) of REM while entering sleep, these irregularities could cause twitches.
If you don't want to experience hypnic jerks, scientists have some suggestions. When you become deeply relaxed, you can learn how to reconnect your body with your brain slowly by moving your fingers and toes a little bit. Then start to move your head and open your eyes so that you can avoid the muscle twitches.
But experts agree that hypnic jerks, though sometimes scary, are harmless. If it wakes you up, simply roll over and go back to sleep, But keep in mind: a caffeinated drink, exciting evening activities or stress may make hypnic jerks happen more often.
