Hypnic jerk: Why do I feel as if I'm falling?

Have you ever experienced the sensation of falling as you drift off to sleep?

The feeling is so real that you jerk awake abruptly and even feel a sense of panic and fear. You may feel your heart racing and your breathing rate may increase. That moment of falling is so real that you can't imagine it was only a dream, especially since you don't even feel like you were actually sleeping. Maybe this hasn't happened to you directly but you have witnessed the action of the sudden jump awakening with your partner or your parent who has fallen asleep in the recliner after the evening meal.

Believe it or not, there is a term for this falling sensation accompanied with fear. What you have just experienced is known as a hypnic jerk or sleep start.

A hypnic jerk is an involuntary muscle twitch that occurs as you begin to fall asleep. It occurs as your sleep paralysis stage of brain activity fights off the last of your awake, stored muscle energy.

One could make a comparison of this behavior as the brain's wrestling match between sleep and wake stages in which neither side wants to lose.

While there is no distinct cause for this involuntary muscle reaction, there has been literature to suggest a link between the hypnic jerk action and things such as stress, sleep deprivation, caffeine or strenuous activities before a person's bedtime. This phenomenon can also be experienced more in an individual who is accustomed to shift work and does not have a regular sleeping routine.

This hypnic jerk action is common and harmless to the individual even though one may have the sensation of fear after the experience. In fact, this activity does occur in individuals who are completely healthy.

If and when it happens to you, just take a few deep breaths, look around, reorient yourself to your surroundings and relax.

If you are still unsure and have concerns about your sleep disturbances or those of a loved one, seek advice and consultation from a physician or call the Blue Mountain Health System's Sleep Center at 610-826-1216 for more information.

Janine M. Mack is the assistant director of Cardiopulmonary Services, Blue Mountain Health System