#27: The Hypnic Jerk

Have you ever had this feeling of slipping and falling very suddenly as you fall asleep? We’ve all had this feeling at least once before, and some have it more often than others. You know what we’re talking about- that involuntary muscle movement that happens suddenly as we fall asleep.

There are many theories suggesting an explanation for this phenomenon. One theory suggests the hypnic jerk goes back to our primate ancestors; it would jerk them awake and prevent them from falling out of trees while sleeping. Another possible explanation relates to stimulants like caffeine, stress and anxiety.