If you’ve ever been drifting off to sleep but suddenly wake with a jolt and a jerk of the body, you’ve experienced a hypnogogic jerk. Named for the transitional period between wakefulness and sleep, these involuntary twitches resemble the “jump” you may experience when you’re startled or scared.

Sleep myoclonus causes involuntary muscle twitches during sleep or when a person falls asleep. In some cases, sleep myoclonus occurs on its own without an identifiable cause. Sleep myoclonus can also develop as a result of a sleep disorder or a neurological disorder.

Sexsomnia or sleep sex occurs when an individual engages in sexual acts while asleep. Most available research has found that sexsomnia episodes occur mostly during non-rapid-eye-movement (NREM), the dreamless, deepest stage of the sleep cycle.

Hypnic jerks — also called sleep starts — are sudden, involuntary muscle contractions you may experience as you are falling asleep1. Hypnic jerks are a type of myoclonus2, which is a category of rapid, involuntary muscle movements. Hiccups3 are another type of myoclonus.

Stress – Anxiety and stress can cause twitching by releasing neurotransmitters from the nerves supplying the muscles. Also, anxiety can make you hyperventilate, or breathe faster, which changes the ions concentration and pH in your body, and predisposes you to muscle twitching.

Movement plays a role in sleep — involuntary twitches commonly take place during rapid eye movement (REM) sleep, but these jolts occur with dreams whereas hypnic jerks occur before the body can dream.

Some patients may have a feeling of having lived a certain experience in the past, known as “déjà vu.” Other warning signs preceding seizures include daydreaming, jerking movements of an arm, leg, or body, feeling fuzzy or confused, having periods of forgetfulness, feeling tingling or numbness in a part of the body.

A rigor may involve violent and uncontrollable shivering, sometimes with mild confusion, but the patient remains conscious and can respond to you. A seizure may also involve jerky shiver-like movements, but patients are not aware of their surroundings and do not respond to you.

Fear, excitement, or stress Strong emotions can cause a person to shake or shiver. This is often due to a surge of adrenaline in the body. Adrenaline is a hormone that triggers the body’s fight-or-flight response. Shivering should stop after the adrenaline leaves the body.

For some people with epilepsy, seizures are preceded by a warning. Doctors refer to that warning as an aura, an event that can manifest as music, swirling colors, a memory, a sense of impending doom, a smell or taste, a rising nausea, or an intense sensation of déjà vu.

General symptoms or warning signs of a seizure can include:

1. Staring.
2. Jerking movements of the arms and legs.
3. Stiffening of the body.
4. Loss of consciousness.
5. Breathing problems or stopping breathing.
6. Loss of bowel or bladder control.
7. Falling suddenly for no apparent reason, especially when associated with loss of consciousness.