As you fall asleep, your body slowly relaxes. Usually you become less aware, so you do not notice the change. However, if you remain or become aware while falling asleep, you may notice that you cannot move or speak.

During sleep, your body alternates between REM (rapid eye movement) and NREM (non-rapid eye movement) sleep. One cycle of REM and NREM sleep lasts about 90 minutes. NREM sleep occurs first and takes up to 75% of your overall sleep time. During NREM sleep, your body relaxes and restores itself. Your muscles are "turned off" during REM sleep. If you become aware before the REM cycle has finished, you may notice that you cannot move or speak.

Sleep paralysis may run in families. Other factors that may be linked to sleep paralysis include:

• Lack of sleep
• Sleep schedule that changes
• Mental conditions such as stress or bipolar disorder
• Sleeping on the back
• Other sleep problems such as narcolepsy or nighttime leg crames.
• Use of certain medications , such as those for ADHD
• Substance abuse

If you find yourself unable to move or speak for a few seconds or minutes when falling asleep or waking up, then it is likely you have isolated recurrent sleep paralysis. Often there is no need to treat this condition.

Check with your doctor if you have any of these concerns:

• You feel anxious about your symptoms
• Your symptoms leave you very tired during the day
• Your symptoms keep you up during the night

Most people need no treatment for sleep paralysis. These treatments may include the following:

• Improving sleep habits -- such as making sure you get six to eight hours of sleep each night
• Using antidepressant medication if it is prescribed to help regulate sleep cycles
• Treating any mental health problems that may contribute to sleep paralysis
• Treating any other sleep disorders, such as narcolepsy or leg cramps

There's no need to fear nighttime demons or alien abductors. If you have occasional sleep paralysis, you can take steps at home to control this disorder. Start by making sure you get enough sleep . Do what you can to relieve stress in your life -- especially just before bedtime . Try new sleeping positions if you sleep on your back. And be sure to see your doctor if sleep paralysis routinely prevents you from getting a good night's sleep.