Iron, Restless Legs, and Sleep

A Conversation with Dr. William Lu on Ferritin, Dopamine, and Restless Leg Syndrome

Guest: Dr. William Lu — Family Medicine, Sleep Medicine & Obesity Medicine

Host: Natalie Walton — GM, BetterSleep

Podcast: The Rest Report

Topic: How iron deficiency affects sleep, energy, and restless legs

Introduction

Natalie: Welcome back to The Rest Report. I'm Natalie Walton, General Manager of BetterSleep. Today we're talking about nutrition — more specifically, how iron levels impact our sleep and wellness. To help us understand this better, I'm joined by Dr. William Lu. William, it's great to have you on the show.

Dr. Lu: Hi Natalie. Thank you so much for having me here. I look forward to speaking with you about iron levels and how they can impact our sleep.

Natalie: Before we dive in, could you share a little about your background and specialization in this area?

Dr. Lu: My primary specialty is family medicine — I'm a primary care physician. I also have additional board certifications in sleep medicine and obesity medicine. I've been caring for patients in these different fields for a number of years, and I've taken care of a lot of patients with low iron levels and seen how that specifically can impact sleep.

A Personal Iron Story

Natalie: Part of the reason this conversation is so exciting to me is that I have a deeply personal experience with iron. I gave birth to my son in 2019. I had a placental abruption where I lost a lot of blood. For the years after, I really struggled with my energy levels. I saw many doctors — a lot of them said, "oh, you're a new mom, you're a founder, it's the pandemic" — every excuse in the book. It got to a point where I was napping every day, really struggling to function as a human.

Natalie: In 2025, I decided to get a Function Health blood test, and it showed that my ferritin levels were 12. That seemed alarming to me when I looked at the range. I went to Dr. ChatGPT, started doing some sleuthing, and ultimately decided I needed to get iron in my system fast. I went to a local place where I got two iron IV infusions over a couple of weeks. It took my ferritin from 12 to around 120–130. I swear, I'm 40 years old, and I felt like a 25-year-old. As a doctor who specializes in this — what was happening? And is this common?

Dr. Lu: First, I'm sorry to hear about your experience. It's always really tough when you're feeling a certain way and everyone tells you, "oh, it's your new child," or it's factors outside of your control.

Dr. Lu: Let me identify a few things that happened. You had a pretty significant amount of blood loss during your pregnancy with that placental abruption. Generally, the first things that come after a pregnancy — especially after there's been a lot of bleeding — should be checking to make sure your iron levels and your hemoglobin (the red blood cells that carry oxygen around your body) are coming up appropriately. That's one thing that should always be checked after a pregnancy like that.

Dr. Lu: I'm really happy you were eventually able to catch this through Function Health — to catch that your ferritin level, the iron stores in your body, was really low. I frequently find that many patients actually don't know their iron stores are low. The reasons can include blood loss for various reasons: post-pregnancy, or even menstrual cycles. Blood loss can really lead to low iron levels.

Dr. Lu: What was happening is that if those iron levels weren't there, your body wasn't producing sufficient red blood cells to carry oxygen around. That's probably what led you to feel more tired and why you needed to nap. From the sleep aspect, if you have low iron and low ferritin levels, you can actually lack the ability to produce enough dopamine in your brain — and that can lead to more interrupted sleep, inability to fall asleep at appropriate times, and more disjointed sleep throughout the night.

What Is Restless Leg Syndrome?

Natalie: That's so fascinating. Can you help me understand how iron deficiency fits into restless leg syndrome — and for people who don't know, what is restless leg syndrome?

Dr. Lu: It's good to understand what restless leg syndrome is. It's what we call a clinical diagnosis — there's really no test for it. The only way we diagnose restless leg syndrome is by asking patients about their symptoms.

Dr. Lu: This might sound like something out of a Halloween show, but patients generally describe the symptoms this way: at night — and generally at night — they feel sensations in their legs. Those might be soreness, a feeling like spiders crawling up and down their legs, or electrical shocks. For every person, it's a unique set of potential symptoms.

Dr. Lu: What's causing this? There can be some genetic predispositions — if your mother or father had restless leg syndrome, you may have a higher risk. But there's also a primary association with low ferritin, those iron stores. Going back to dopamine — everyone thinks about dopamine as that feel-good hormone. If you don't have sufficient iron, you won't be able to produce enough dopamine, and the result is you can develop the symptoms of restless leg syndrome.

How to Tell If Iron Deficiency Is the Root Cause

Natalie: Iron deficiency can lead to so many things — restless leg syndrome, and whatever I had, which I knew was impacting my sleep. How does someone know if iron deficiency is the root cause of their sleep issues?

Dr. Lu: It can be tough to find this out. The only way to really know your ferritin and iron levels is a blood test. A lot of this depends on patients telling their providers about their symptoms — and even then, iron and ferritin are not typically standard blood tests ordered at primary care checkups or as baseline labs. So it can be missed. It can be tough to catch these symptoms, especially if patients don't have awareness that it's happening.

Dr. Lu: I've heard patients describe restless leg syndrome as, "yeah, I just feel this thing happen when I'm sitting on my couch," but they never really thought more about it. We think restless leg syndrome affects anywhere from one in six to one in 20 people worldwide. It's a common disease — yet there's so little we're doing to catch it and help patients with these symptoms.

Natalie: If you don't know, you don't know. That's why having conversations like this is so important. If you can't sleep, it's really the worst thing — I did not sleep for five years. Besides restless leg syndrome, are there other conditions an iron deficiency can impact on your overall sleep health?

Dr. Lu: Low iron is most associated with restless leg syndrome. There's lesser evidence about how iron deficiency anemia on its own impacts sleep — the evidence isn't as strong, but over time we're probably going to find more associations. Even without a restless leg diagnosis, if you have insufficient iron, you may experience worse quality sleep as well.

The Restless Legs Paradox

Natalie: Something I find interesting about restless leg syndrome — I've kind of experienced this, some tingling in my legs, particularly during pregnancy. I don't know if it comes up more during pregnancy, but I'd always feel this weird feeling, like a reflex that I needed to stretch my legs. It kind of went away after pregnancy. But it's a paradox: many people with iron deficiency feel exhausted and experience restless leg syndrome and can't sleep. Why does having movement in your legs disrupt your sleep?

Dr. Lu: Great question. Restless leg syndrome is very common in pregnancy — being pregnant can actually be a risk factor for developing symptoms. However, once the baby is born, we expect symptoms can improve or even resolve. It can show up in your second or third trimester and then disappear from there.

Dr. Lu: Iron deficiency and restless legs can show up in so many different ways. When you're iron deficient, you're going to be tired during the day. Yet when you're trying to sleep at night with restless legs, you might have a much more difficult time falling asleep. Imagine lying in bed — you're already tucked away there, but you feel this itch in your legs that won't go away. You might lie there for 30, 60, 90 minutes trying to fall asleep until finally you're so tired that you can really achieve sleep.

Dr. Lu: That's not the end of it. If you're waking up in the middle of the night to use the bathroom — or, restless legs can even be associated with something called periodic limb movements of sleep, where you continue to move your legs while you're sleeping. This is a factor of your brain being in a hyperactive state because of the low dopamine levels. You're actually in overdrive. The movements are almost a symptom of the low dopamine and low iron levels.

What to Do If You Suspect Iron Deficiency

Natalie: Let's get into the fix. If someone suspects iron deficiency is causing restless leg syndrome, or like me, they've given birth, or maybe they're struggling with heavy menstruation and sleep problems — what's the first step they should take? Are there lifestyle or nutrition things to consider?

Dr. Lu: The first step is just listening to your body. If you're feeling tired, or you find you need to nap frequently when that wasn't the case before, identifying that something has changed is really important. We know our bodies best — that's the first step to alerting us that something might be off.

Dr. Lu: The next step is getting the objective data: do you have a low iron level? Is your ferritin really decreased? Because ultimately, if it's not, we have to look elsewhere for the origin of the symptoms. Making sure you're established with a primary care provider who will listen and address those concerns is a really important piece.

Dr. Lu: If we do find low iron, I recommend iron supplementation. There are many good, clean iron supplements that can be taken daily. We always want to be a little cautious — taking iron can cause symptoms like constipation or dark stools. Use it cautiously to get to the right place. Once you start to supplement — or in your case, with an iron IV infusion if necessary — we can see symptoms start to improve. For some patients, RLS might disappear completely.

What Recovery Looks Like

Natalie: My personal experience was that within three or four weeks, I started to get a buzz — I thought, "what, am I in college again? I can stay up late, go on walks, don't have to take naps." It was miraculous for me. Not everyone is the same, but from your medical perspective, as iron levels begin to recover, what improvements in restless leg syndrome and sleep quality typically show up first?

Dr. Lu: It depends on what the iron deficiency was causing. Was it causing anemia and daytime symptoms, or more of the restless legs and nighttime symptoms — or maybe both? Once your iron starts to improve, your red blood cell count goes back up, and dopamine production starts to occur again within the brain, we should anticipate that symptoms get lighter.

Dr. Lu: You might have more energy during the daytime. You stop feeling those symptoms in your legs, and it becomes easier to fall asleep. You might notice you wake up with a little more energy, or that you feel more well-rested. It's usually not overnight that you'll see a disappearance of symptoms — you'll probably see gradual improvement over weeks to months, similar to your experience.

Natalie: That's what I experienced, and that's why I'm such a fan. I encourage everyone, if they're struggling, to get tested and get that information — because there's hope. There's something on the other side of that. If you've been struggling for years, that's all you want: hope. This is not a permanent situation.

How BetterSleep Supports Recovery

Natalie: How can BetterSleep help someone cope with restless leg syndrome or anemia — someone struggling with middle-of-the-night wakeups or needing to nap? How can BetterSleep help improve sleep quality during this recovery period?

Dr. Lu: One thing that's really mysterious to patients is that we don't really know when we're falling asleep, and we don't know how long we're sleeping for. Some of the features with BetterSleep — sleep tracking, seeing how long it takes you to fall asleep — are valuable. If you're lying in bed listening to relaxing sounds or storytelling and thinking, "yeah, I'm doing this for an hour or two hours," that might be your signal that something is off, for whatever reason.

Dr. Lu: Having more objective measures can be very powerful. It can give validation to users about what might be happening before and during their sleep.

Closing

Natalie: That's my hope — that we can educate our users, help them understand what's going on, and through conversations like this, direct them to the help they need. This has been so valuable for me as someone who struggled with the exact thing you treat. Thank you for helping our audience understand how iron affects their sleep. What's the best way for people to find you or access resources?

Dr. Lu: I'm currently at a telehealth sleep clinic called Dream Health (DRM). We take care of patients across the country in all 50 states, ranging from sleep apnea to restless leg syndrome to insomnia. We really want to take care of patients in all aspects of sleep — whole care is so important, and sleep is just so important to our health.

Dr. Lu: If people are looking for more resources on restless leg syndrome specifically, check out rls.org — the Restless Legs Syndrome Foundation. They're a nonprofit group advocating for people with RLS and getting the word out that this condition exists. Many people have these symptoms. If you're experiencing these symptoms or can relate, seek help. Better sleep is really around the corner, and there are many ways we can help address it.

Natalie: Thank you so much. To our audience — thank you for watching The Rest Report. If sleep has been a struggle for you, there is real hope. These challenges are surmountable with the right guidance. Subscribe to our podcast and newsletter for the latest resources, and follow BetterSleep on our socials. You can visit us at bettersleep.com for simple, soothing content to help you rest. See you in the next episode. Thank you so much, William.

Dr. Lu: Thank you so much, Natalie.

— End of Transcript —