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Low Iron & Vitamin D Levels Are Linked To Sleeping Poorly, New Study Shows

Author:

Molly Knudsen, M.S., RDN

December 27, 2023

Registered Dietitian Nutritionist

By Molly Knudsen, M.S., RDN

Registered Dietitian Nutritionist

Molly Knudsen, M.S., RDN is a Registered Dietician Nutritionist with a bachelor’s degree in nutrition from Texas Christian University and a master’s in nutrition interventions, communication, and behavior change from Tufts University. She lives in Newport Beach, California, and enjoys connecting people to the food they eat and how it influences health and wellbeing.

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Image by SERGEY FILIMONOV / Stocksy

December 27, 2023

There's a lot that can stand in your way to a good night's sleep. While screen use, noisy neighborhoods, or stuffy rooms may be some of the more obvious culprits, your nutritional status also plays a sneaky important role—especially for women.

Two nutrients women commonly fall short on (according to blood work) are iron and vitamin D. Researchers of a new study published in the Journal of Nutrition specifically looked at how the lack of these nutrients impacts the sleep quality of women under 50 1. Here's what they found.

About the study

Researchers collected data from almost 10,000 women of reproductive age (between the ages of 20 and 49) in the United States. The women underwent blood testing, which revealed:

13% had iron deficiency (low iron levels)
6% had iron deficiency anemia (low iron and hemoglobin levels)
8% had a vitamin D deficiency (typically blood levels below 20 ng/mL)
30% had insufficient vitamin D levels (typically blood levels between 20 and 30 ng/mL)

They then completed a questionnaire asking about how long they usually sleep, how long it takes them to fall asleep, and the quality of their sleep. (Note: This method isn't quite as objective as using a wearable sleep tracker, but the data still provides valuable insights.)

The connection between vitamin D, iron, and sleep

After analyzing all these inputs, researchers found that not having enough of these nutrients was indeed significantly linked to poor measures of sleep in the following ways:

Women with iron deficiency had a 42% higher likelihood of struggling with sleep quality
Women with iron deficiency anemia are more than twice as likely to struggle with sleep quality
Women with deficient and insufficient vitamin D levels have 26% and 22% higher odds of sleeping less
Women who were deficient in both iron and vitamin D were the most likely ones to experience sleep challenges

These findings align with past research. So going into this study, the researchers already knew that low levels of iron and vitamin D are detrimental to sleep.

For example, vitamin D is involved in the body's natural production of melatonin 2 (the hormone that helps regulate your circadian rhythm, making you feel sleepy). And while low vitamin D can hurt your sleep, not sleeping enough 3 can also worsen your vitamin D levels. It's a dangerous cycle.

Several sleep concerns are also correlated with iron deficiency. Common side effects of iron deficiency (like dizziness, lightheadedness, and mood changes) can also impact sleep.

But this study captured just how much these (often unseen) factors impact sleep among women prior to menopause.

How to get your iron & vitamin D levels checked

Most women likely don't know their iron and vitamin D status. That's concerning because while iron deficiency anemia is rare in men, its prevalence is much higher in women, affecting about 9-12% of white women and nearly 20% of Black and Mexican American women. And low vitamin D levels are low across the board. About 29% of adults in the U.S. are deficient in the vitamin, and a whopping 41% are insufficient 4.

But the best blood markers of iron status (ferritin) and vitamin D (25-hydroxyvitamin D) aren't included in standard insurance-covered blood work.

While functional medicine practitioners likely include these labs for their patients, many traditional docs don't. So, if you're tossing and turning and waking up each morning exhausted, consider asking your health care practitioner to run these blood tests, or opt for an at-home testing option (this is our favorite for iron, and here are our top choices for vitamin D).

Moving from insufficiency to optimized

ultimate multivitamin+

To raise these levels, make sure to include iron-rich foods in your diet (think animal proteins, soybeans, and spinach) and sources of vitamin D (like salmon, trout, and fortified milks).

But for many people, diet alone isn't enough to move from insufficient to optimal levels of these nutrients (especially vitamin D), and adding a high-quality supplement to your day will be your best bet for making a meaningful difference.

mindbodygreen formulated ultimate multivitamin+ with meaningful doses of both iron and vitamin D to help address these nutrient gaps.* Many people find iron supplements to be hard on the stomach, but each mineral included in ultimate multivitamin+ is in its most gentle and bioavailable form.* It's an easy daily solution to make sure you're getting the right amounts of the nutrients you need for health (and sleep).*

If you'd rather go for just a vitamin D supplement, we have a list of our dietitian-vetted favorites here.

The takeaway

Running low on iron or vitamin D may be one reason you're not getting the sleep of your dreams. Setting your room and sleep routine up for success is absolutely important to getting quality shut-eye, but don't overlook getting an iron and vitamin D blood test now and then to check on your levels. And if they aren't where they should be (or you need some support in keeping them optimized), reach for a high-quality multivitamin that supplies both of these nutrients, like ultimate multivitamin+.*

If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.