Sleep robbers: RLS and periodic limb movement disorder

Sleep apnea is just one of several disorders that can deprive you of valuable sleep. This week and next, we’ll discuss the symptoms and treatments of two similar limb movement disorders that each affect roughly 1 in 10 adults: Restless legs syndrome (a/k/a restless leg syndrome, RLS) and periodic limb movement disorder (PLMD).

RLS symptoms vs. PLMD symptoms

When you’re awake, RLS can make it difficult to fall asleep. While you’re awake, this neurological syndrome causes uncomfortable, “creepy-crawly” and sometimes painful sensations in the legs, resulting in the uncontrollable urge to move them. These sensations usually occur within 15 minutes of lying or sitting down, and can also affect the arms, torso or even a phantom (amputated) limb.

When you’re asleep, PLMD can wake you repeatedly throughout the night. It causes an involuntary kicking or jerking movement of your legs or arms while you sleep. Most people don’t notice they’ve woken, the same way we’re almost never consciously aware of our apneas.

Both disorders occur more frequently in women and in people over 65. And of course, both disorders can disturb your bed partner’s sleep as well as your own.

Causes of RLS and PLMD

The primary cause of both disorders is unknown. However, research tells us:

• PLMD can be caused by some medications, particularly antidepressants.¹
• Both PLMD and RLS can be brought on by low levels of iron – and treating your iron deficiency can potentially eliminate symptoms.
• RLS may be genetic; nearly half of those who have RLS also have a family member who has it.²
• RLS develops or worsens in 1 of 4 pregnant women,² especially after Week 20.³ But when it develops during pregnancy, it usually goes away within 4 weeks after delivery.⁴

Also, 80% of those with RLS also have PLMD,⁵meaning their limb movements make it hard to fall and stay asleep. However, those with PLMD are not more likely to have RLS.

Getting tested for RLS or PLMD

RLS is not diagnosed through a specific test. Instead, your doctor will determine if you have it, and with what severity, based on these five criteria:

1. A strong, often overwhelming urge to move legs or other limbs.
2. These urges are triggered by rest, relaxation or sleep.
3. These urges are worst at night, and not noticeable or problematic in the morning.
4. These urges are relieved with movement, but resurface after the movement stops.
5. It’s likely mild/moderate if your symptoms aren’t particularly painful and occur once a week or less; it’s likely severe if your symptoms are painful and/or occur 2+ times a week.

PLMD should be suspected if you wake up in a disheveled bed (pictured) or your bed partner complains of being woken during the night by your flailing arm or leg. But it’s best diagnosed by a polysomnogram (PSG), the same overnight sleep lab test that can diagnose sleep apnea and other sleep disorders by monitoring your vital signs and movement while you’re in bed.

Next week: Treating RLS and PLMD

There is no cure for either disorder. But there are various treatment options, and they’re somewhat similar for each. This is particularly good news for anyone who has both RLS and PLMD. In our next post, we’ll list these treatments (which you should always discuss with your doctor before starting) – as well as which ones may make obstructive sleep apnea worse in some patients.