Pregnancy already does a number on sleep. Between the trips to the bathroom, the hip pain, the strange dreams, and the small human using your bladder as a trampoline, actual rest can feel like a distant memory. But there's one particular sleep disruptor that researchers are starting to pay closer attention to — and it may matter for more than just how tired you feel in the morning.

Restless legs syndrome (RLS) is that maddening, hard-to-describe urge to move your legs, usually right when you're trying to settle down for the night. It's uncomfortable, it's persistent, and it turns out it may also be quietly connected to perinatal depression. A recent study out of Japan found that pregnant women who experienced RLS in their third trimester had roughly three times the risk of developing depression during pregnancy or in the months after birth.

That's a striking number, and worth unpacking carefully — because the implications matter for anyone navigating pregnancy, and because the usual advice (“just try to sleep more”) does not cut it here.

What the Researchers Actually Looked At

The analysis drew on data from 2,435 pregnant women who were part of the control group in a larger trial on preventing perinatal depression. Participants filled out questionnaires about restless legs symptoms during their second and third trimesters, and researchers then tracked whether they developed major depressive episodes or notable depressive symptoms up to three months after giving birth.

Over an average follow-up of about six and a half months, 69 women developed perinatal depression. Five of those women had RLS during pregnancy. After adjusting for things like age, education, employment status, and whether the pregnancy was planned, the researchers landed on that threefold risk estimate.

One honest caveat worth flagging: five is a small number. The signal is interesting, but it needs confirmation in bigger studies before anyone treats it as settled science. Still, the pattern lines up with what we already know about sleep, hormones, and mood during pregnancy — which is part of why it's getting attention.

Why Would Restless Legs and Depression Be Connected?

There are a few plausible threads, and they probably work together rather than in isolation.

The most obvious is sleep itself. If your legs are twitching and crawling with that indescribable restlessness every night, you're not sleeping well — and chronic sleep disruption during pregnancy has already been linked to a higher risk of mood disorders. Sleep is not a luxury during these months; it's part of how the nervous system regulates stress, mood, and hormone balance. Knock it out of rhythm for long enough and things start to wobble.

Iron is another suspect. Pregnancy ramps up the body's iron requirements significantly, and iron deficiency has been independently connected to both RLS and depressive symptoms. Low iron can also mess with the brain's dopamine system, which plays a role in mood regulation and reward. If both conditions share an iron-dopamine root, treating the deficiency might ease both — though that's a hypothesis, not a prescription.

Thyroid function has also been floated as a possible shared driver. Pregnancy puts enormous demand on the thyroid, and thyroid imbalance can show up as fatigue, mood changes, and sleep disturbance all at once.

The honest bottom line: nobody has proven that RLS causes depression, or that treating RLS would prevent it. What we have is a correlation worth taking seriously, especially in the third trimester.

When Does RLS Actually Show Up in Pregnancy?

Here's a useful detail from the study: the association with depression showed up when RLS was present in the third trimester, not the second. The condition itself also became more common as pregnancy progressed — about 1.6% of participants reported it in the second trimester, rising to 3.5% in the third.

That timing matters. Late pregnancy is already a vulnerable window: the body is tired, the belly makes any sleeping position a negotiation, and anxiety about labor and parenthood tends to crescendo. Adding a nightly neurological irritation on top of that is a recipe for the kind of exhaustion that erodes mood over weeks.

If you've made it to the second trimester without restless legs, that doesn't mean you're in the clear — and if it shows up in month seven or eight, it's not something to shrug off as a late-pregnancy quirk.

What to Do If Your Legs Won't Settle at Night

None of this is a reason to panic. Most women with RLS in the study did not develop depression. But it is a reason to speak up at your next prenatal appointment rather than toughing it out alone. Here's a practical checklist:

• Notice the pattern. RLS tends to strike when you're sitting still or lying down, especially in the evening. The sensations are hard to describe — crawling, tingling, pulling, an electric itch — but the urge to move is unmistakable, and movement usually brings temporary relief.
• Track it for a week. Jot down roughly when symptoms start, how long they last, and whether they're affecting your sleep. Specifics help your doctor more than vague descriptions.
• Bring it up with your provider. Tell your doctor or midwife, especially if symptoms are new in the third trimester or getting worse. This is not a complaint-too-small situation.
• Ask about iron testing. If your ferritin levels are low, addressing that may ease both the restless legs and your energy overall. Do not start iron supplements on your own — too much iron has its own risks, and your provider should guide the dose.
• Review sleep hygiene with honesty. Caffeine, screens, and irregular bedtimes make RLS worse. None of this will magically fix the condition, but it stacks the deck in your favor.
• Mention your mood. If sleep loss is pushing you into territory that feels darker than tired — persistent low mood, loss of interest, tearfulness, hopelessness — say so. Perinatal depression is treatable, and earlier is always better than later.

The Bigger Picture: Why Small Signals Matter in Pregnancy

One of the quieter frustrations of pregnancy care is how many symptoms get waved off as normal. Tired? Normal. Can't sleep? Normal. Legs weird at night? Normal. And yes — a lot of discomfort during pregnancy is genuinely common and benign. But “common” is not the same as “ignore it.”

Restless legs in the third trimester may be one of those signals that gives providers useful information about depression risk. For an individual woman, it's a nudge to pay attention to sleep, iron, and mental health all together, rather than treating them as separate problems. The nervous system doesn't actually separate them — we just do, administratively.

Perinatal depression affects a meaningful percentage of mothers, and much of it goes undiagnosed because women don't always know what to flag or feel too stretched to raise it. If a nightly leg twitch is the thing that gets you talking to your provider about how you're really doing, that's a win.

A Note on Rest, Recovery, and Looking After Yourself

Sleep, mood, and nervous system regulation are foundational to how we weather any major life transition — pregnancy very much included. Many women look for ways to support this foundation beyond medical care alone, through gentle practices like prenatal breathwork, restorative yoga, meditation, or short wellness retreats designed for the postpartum window. For readers drawn to that kind of restorative experience after pregnancy, a range of calming, nature-based wellness retreats can be browsed on our marketplace here.

If your legs won't let you rest, don't white-knuckle it. Mention it. The study's small size means we shouldn't overread the numbers, but the direction is clear enough: late-pregnancy sleep disruption deserves attention, and so does your mental well-being underneath it.