Iron is a mineral that helps transport oxygen to cells, tissues, and organs. Significant iron deficiency—which can be diagnosed via a standard blood test—may result in anemia (also spelled anaemia), a condition in which blood lacks an adequate supply of red blood cells. It’s estimated that, in developed countries, 20% of adult females suffer from iron deficiency anemia (IDA), with a higher prevalence among pregnant women (50%). The numbers are considerably lower for adult males (3%). (1)

Below, we dive in the science behind how low iron levels affect sleep and overall wellness—and how supplementation can help.

In addition to higher blood pressure and hypertension, (2) anemia is a risk factor for various sleep issues.

Impacting sleep quality

Iron plays an important role in the metabolism of the brain’s monoamines, a term that encompasses the following three neurotransmitters:

  1. Dopamine: affects feelings of pleasure
  2. Noradrenaline: affects attention and motivation
  3. Serotonin: our happy hormone

This is why common symptoms of anemia include apathy, tiredness/daytime sleepiness, irritability, and lack of attention. The same monoamines also impact sleep physiology, which has led researchers to suspect (1) that IDA negatively impacts sleep quality as well as mood and temperament.

Recent studies on the relationship between anemia and insomnia have also revealed that both conditions have a shared gene: MEISI, which plays an important role in iron metabolism and ferritin levels (blood protein that contains iron). (3) This gene is also associated with Restless Leg Syndrome (RLS), which is when your legs feel like they’re tingling, itching, aching, and/or burning when you’re trying to fall asleep.

Triggering Periodic Limb Movement Disorder (PLMD)

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PLMD is characterized by repetitive leg and foot movement in the form of jerks, muscle twitches, cramping, and flexing during sleep (about every five to 90 seconds). Although it may cause you to wake up, it doesn't always—a common symptom is Excessive Daytime Sleepiness (EDS) or fatigue, which causes many to confuse PLMD with insomnia. In many PLMD cases, one’s sleep partner picks up on it first. There are two main types:

  1. Primary
    Primary PLMD is idiopathic, meaning the cause is unknown and the condition appears on its own. 

  2. Secondary
    Secondary PLMD is triggered by a specific cause, such as iron deficiency/anemia, diabetes, over-caffeination, and other sleep disorders such as Restless Leg Syndrome (RLS), narcolepsy, REM sleep behavior disorder, or sleep apnea. It can also present as a side effect of certain medications, including anti-nausea, tricyclic antidepressants, and neuroleptics.

How PLMD is diagnosed:

First, you will likely undergo a routine physical examination to rule out other causes, followed by a polysomnography (PSG) in a sleep lab.

There are many iron-rich foods, notably leafy greens, beef, muscles, oysters, dark chocolate, and lentils—which should be consumed alongside Vitamin C for optimal iron absorption. However, many choose iron supplementation when natural sources aren't sufficiently maintaining or increasing their iron levels.

In a 2020 study (4) published in the National Institute of Health (NIH), 176 participants (138 female and 38 male) with iron deficiency received either intravenous iron or oral iron supplementation for 12 weeks. Results showed a significant improvement in the severity of symptoms for restless leg syndrome, fatigue, and sleep quality. Additionally, participants experienced a significant decrease in headaches, dyspnoea (shortness of breath), and heart palpitations. Results were consistent for both intravenous and oral administration of iron.

  • Standard dosage: 325mg (65 iron) of ferrous sulfate
  • Best absorbed on an empty stomach (1 hour before or 2 hours after eating)

Note that it's always best to consult your healthcare provider before beginning any new supplement regime.

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