Periodic limb movements are episodes of simple, repetitive muscle movements that you have no control over. They usually don't prevent you from falling asleep, but can cause disruptions to your own or your bed partner's sleep cycle at night. Consequently, both of you can suffer from fatigue during the day.
Periodic limb movements don't involve alterations to body position, muscle stretching or cramps. Instead, these typically involve the muscles contracting or flexing - most commonly seen in the lower legs.
They can occur at two different times:
- Periodic limb movements while you sleep
- Periodic limb movements while you are awake
Sleep movements are fairly common, and can interfere with quality rest when they happen frequently throughout the night. Most people don't realize they're happening until morning, or ever.
The big toe typically extends and it may be accompanied by a slight bend at the ankle, knee or hip. On rare occasions, this can even occur in the upper arms.
The intensity of these movements may fluctuate from night to night. Typically, they take place during non-rapid eye movement sleep in the early hours of the evening. When they become extremely severe, they can even manifest while you are awake.
An episode usually lasts from a few minutes to an hour, wherein movements take place approximately every 20 to 40 seconds. These can affect either one or both legs.
Limb movements during slumber are normal for many individuals; usually not affecting their sleep in any major way. Consequently, it is not considered a sleeping disorder - though the bed partner's rest may be more subject to interruption.
When these movements reach an extreme level, they can become a condition known as periodic limb movement disorder, which can affect sleep and daily life.
This disorder may be a factor in causing you to have any of the following:
- Depression
- Bad memory
- Short attention span
- Fatigue