Sleep starts are also known as hypnic or hypnagogic jerks. They are sudden, brief and strong contractions of the body or one or more body segments. They occur as you are falling asleep.

Sleep starts usually consist of one strong jerk that affects much of the body. The arms and legs are most likely to be affected. A sharp cry may also occur. A sleep start does not always wake you up. This means that you may not recall a jerk that was noted by a bed partner.

They sometimes happen along with one of the following impressions:

  • The feeling that you are falling
  • A sensory flash
  • A visual dream or hallucination

The frequency and intensity of sleep starts can be increased by the following:

  • A high intake of caffeine or other stimulants
  • Prior intense physical work or exercise
  • Emotional stress

At times, many jerks may occur one after another. They can be frequent, intense, and repetitive. Intense or frequent sleep starts may lead to a fear of falling asleep. This can also lead to anxiety and worry.

Sleep loss may result if repeated jerks keep you awake. Anxiety caused by the sleep starts can also make it hard to fall asleep. Chronic insomnia can result if this problem continues over time.

It is possible to be injured by a sleep start. The jerk may cause you to bruise a foot against the bed or kick a bed partner.

Who gets it?

Sleep starts are a very common part of the process of falling asleep. They may not seem so common because they often are not recalled. They have been reported to occur in 60% to 70% of people.

In most people, they only occur from time to time. Sleep starts affect all ages and both men and women. Adults are more likely to complain about frequent or intense jerks.

 How do I know if I have it?

  1. Do you have sudden, brief jerks of your body as you fall asleep?
  2. Do these jerks mainly affect your arms and legs?
  3. Do they occur along with one or more of the following sensations?
    • A feeling that you are falling
    • A sensory flash
    • A visual dream or hallucination

If you answered yes to these questions, then you might have sleep starts.

It is also important to know if there is something else that is causing your sleep problems. They may be a result of one of the following:

  • Another sleep disorder
  • A medical condition
  • Medication use
  • A mental health disorder
  • Substance abuse

 Do I need to see a sleep specialist?

Sleep starts are very common and do not require treatment in most people. You should see a sleep specialist if the jerks, or your fear of them, are keeping you from getting enough sleep.

 What will the doctor need to know?

First, the doctor will need to know when the sleep starts began. He will also want to know what else has been going on in your life. You should complete a sleep diary for two weeks. This will give the doctor clues as to what might be causing you problems. You can also rate your sleep with the Epworth Sleepiness Scale. This will help show how your sleep is affecting your daily life.

The doctor will need to know your complete medical history. Be sure to inform him of any past or present drug and medication use. Also tell him if you have ever had any other sleep disorder.

Will I need to take any tests?

No tests are needed to detect sleep starts in most people. Your doctor may have you do an overnight sleep study if your jerks are severe. This study is called a polysomnogram.

It charts your brain waves, heart beat, and breathing as you sleep. It will also record how your arms and legs move. This will also show if there are other disorders, such as sleep apnea, that are causing your sleep problems.