You’re drifting into sleep when suddenly—you feel like you’re falling, and your body jerks awake. This common phenomenon is called a hypnic jerk (or sleep start), and up to 70% of people experience it.
What Are Hypnic Jerks?
They’re involuntary muscle spasms that happen as you’re dozing off, often with a sensation of falling. They’re harmless but can be startling.
Why Do They Happen?
Scientists have two main theories:
Nervous system misfire: As your body slows down for sleep, the nervous system briefly misfires.
Brain’s false alarm: The brain mistakes muscle relaxation for falling and jolts the body as a reflex.

Triggers
They’re more likely with caffeine or nicotine, lack of sleep, stress, irregular schedules, or stimulant medications.
Are They Normal?
Yes—hypnic jerks are natural and not a disorder. Still, frequent ones can disturb sleep.
How to Reduce Them
Limit caffeine/nicotine late in the day
Avoid vigorous late exercise
Try relaxation before bed
Keep a steady sleep routine

Manage stress with mindfulness or yoga
Bottom Line
Hypnic jerks may feel unsettling, but they’re normal. Small lifestyle changes can help reduce them so you can rest easier.