Nighttime (nocturnal) seizures cause unusual movement or behavior during sleep, including waking for no clear reason, violent arm or leg movement, tongue biting and urination. People with nocturnal seizures are often unaware of what's happening and may mistake their daytime fatigue for effects of insomnia.

Nocturnal seizures are abnormal electrical activity that occurs in your brain when you sleep. They're most often linked to epilepsy, but they can also happen in people who don’t have a diagnosed seizure disorder.

Some types of epilepsy, like frontal lobe epilepsy, are more likely to cause seizures during sleep. Other factors, such as sleep deprivation, stress, fever and certain medications, can also increase the chances of a nighttime seizure.

Since nocturnal seizures happen while you’re sleeping, you may not realize you’re having them. But you or a bed partner may notice signs, such as:

• Sudden, unexplained waking
• Rhythmic or jerking movements of the arms or legs
• Stiffening of the body
• Tongue biting
• Urinary incontinence
• Unusual sounds, like groaning or crying out
• Confusion or disorientation upon waking

Unusual fatigue, morning headaches and trouble concentrating can also be signs of nocturnal seizures.

Nocturnal seizures are more likely to occur while you’re lightly sleeping, during the stage that happens soon after you fall asleep or just before you wake up. They can also occur during daytime naps.