You’re in your third trimester and you start to be jerked out of sleep because your leg is kicking uncontrollably. Maybe you kicked off the covers or kicked your sleep partner. After a few nights of kicking and waking, you are exhausted during the day. You could be experiencing a sleep movement disorder that is more common during pregnancy, called periodic limb movement disorder (PLMD).
PLMD is a close cousin of another movement disorder in pregnancy, restless leg syndrome (RLS). You can read about RLS here. RLS causes the uncomfortable sensation of an irresistible urge to move your legs. This urge occurs when you rest or lie down. Like PLMD, RLS can interfere with sleep. However, the symptoms of PLMD are different and very specific.
Symptoms of PLMD
Unlike RLS, which can occur anytime your legs are at rest, PLMD only occurs during sleep. PLMD usually occurs in the first 90 minutes after falling asleep, a period called non-REM sleep. PLMD can occur in one or both legs. PLMD can occur any time during pregnancy, but is most common during the third trimester. Symptoms can include:
- Extension (bending upwards) of the big toe
- Flexion (bending downwards) of the ankle
- Bending the knee
- Bending the hip
- Movements that occur repeatedly every 5 to 90 seconds
Rarely, movements of the arm or arms can also occur. You should know that many people who have RLS will also develop PLMD. RLS may affect up to one in five pregnant women, so there is a good possibility that your earliest warning for PLMD could be an irresistible urge to move your legs. RLS is relieved by getting up and stretching your legs or walking.
What Causes PLMD?
The causes of RLS and PMLD are not completely known, but they are probably similar. Outside of pregnancy, both conditions are more common in the elderly and are probably due to a loss of a brain chemical (neurotransmitter) called dopamine. Decreased production of dopamine is also the cause of Parkinson’s disease. During pregnancy, loss of dopamine may be related to a deficiency in folate or iron, or to pregnancy hormones.
Both folate (vitamin B-9) and iron are used up more quickly during pregnancy. That’s why they both may be part of your prenatal vitamin supplements. Reduced amount of folate or iron may lead to a decreased production of dopamine. Two pregnancy hormones have been linked to decreased levels of dopamine, progesterone and prolactin. Dopamine is a neurotransmitter that helps control muscle movements.
Diagnosis and Treatment of PLMD in Pregnancy
Your health care provider will probably diagnose PMLD by your symptoms. If in doubt, you may have a sleep study. If your health care provider suspects PLMD, you may also have your blood iron and folate levels checked.
During pregnancy, the first treatments for both RLS and PLMD are lifestyle changes. If you have low levels of iron or folate, these can be treated with supplements. These are the recommendations for lifestyle changes:
- Avoid caffeine, which may trigger PLMD, that includes caffeine in coffee, tea, chocolate, and soft drinks.
- Try relaxing your leg muscles before bed with a massage or a warm bath.
- Keep to a healthy sleep routine, going to bed and waking at about the same time and sleeping in a quiet dark room.
- Get regular leg exercise every day, this will make your leg muscles less sensitive at night.
- Ask you health care provider if you are on any medication that may trigger PLMD. These meds include antidepressants, anti-nauseas, and antihistamines.
For people who are not pregnant, several medications can help. For pregnant women, however, most of these medications are not considered safe. If you are really suffering and losing sleep, your health care provider may consider a muscle relaxant or anti-anxiety medication (benzodiazepine).
The good news is that the outlook (prognosis) for PLMD during pregnancy is better than outside of pregnancy. When older people get PMLD or RLS, it is usually a long-term problem without a cure. When these movement disorders occur during pregnancy, they usually go away after delivery.
One final thing. If you are waking up tired and your sleep is restless, ask your sleep partner if you are jerking or kicking in your sleep. Some people may have PLMD that disrupts their sleep but does not completely wake them up.