If you have anemia, you might feel tired and run-down some, or even a lot, of the time. Tiredness and fatigue are common symptoms of anemia, which causes a lack of sufficient oxygen supply to the cells and tissues of the body. Lack of focus and mental sluggishness also occur for some people with anemia, as do mood problems including anxiety and depressive symptoms.
Tired, fatigued, distracted, low, anxious, irritable mood—sounds a lot like sleep deprivation, right?
Anemia and poor sleep share several of the same symptoms. And, according to some important recent research, they also share some genetic connections.
Recent studies have identified a gene that is associated with both insomnia and with iron-deficiency anemia, the most common form of anemia.
The relationship between anemia and poor sleep hasn’t gotten a great deal attention in scientific research. We’ve seen research showing iron-deficiency anemia is linked to lower sleep quality, and a small group of studies showing an association between insomnia and anemia in adults. And iron-deficiency anemia has also been linked to restless legs syndrome.
But there is a crop of recent research, including these genetic studies and other new research on the relationship between anemia and insomnia, that demonstrates important connections between iron-deficiency anemia and chronic poor sleep.
The basics of anemia
Before we look at the latest science on anemia and insomnia, let’s do a quick rundown of anemia itself.
Anemia occurs when the body doesn’t have a sufficient supply of red blood cells. Red blood cells are responsible for delivering oxygen throughout the body, and for taking carbon dioxide from the cells and tissues of the body to the lungs, where it is exhaled.
There are many different types of anemia. The most common form of anemia is caused by a lack of sufficient iron. Iron is needed to produce a protein, hemoglobin, which is contained within red blood cells and enables these blood cells to transport oxygen. Iron-deficiency anemia is responsible for approximately 50% of all anemias diagnosed worldwide.
Iron-deficiency anemia can be caused by a lack of sufficient iron in diet, problems with iron absorption, blood loss, and in some cases, infection. Pregnancy, which increases a woman’s need for iron, also causes anemia.
Risks for iron-deficiency anemia vary based on several criteria, including age, gender, ethnicity, and socio-economic factors:
- Iron-deficiency anemia becomes more common with age
- Women are at higher risk for this form of anemia than men
- Pregnant women are at particularly high risk for iron-deficiency anemia. An estimated 20% of women, and 50% of pregnant women in developed countries have iron-deficiency anemia, according to research.
- Approximately 10% of women who menstruate have iron-deficiency anemia
- Being Black or Hispanic increases risks for anemia
- Adults and children in low-income families have higher risks of iron-deficiency anemia
Anemia is diagnosed by blood tests that measure red blood cells and hemoglobin. Hemoglobin levels of less than 13.5 gm/dl in men, and less than 12 gm/dl in women, indicate anemia. In recent decades, rates of anemia in the US have grown substantially, nearly doubling between the years 2003-4 and 2011-12, according to research.
The symptoms of anemia can vary. Sometimes anemia is present without symptoms.
Feeling tired and sluggish, experiencing weakness, and lacking the energy to meet the demands of daily life is common among many people with anemia. Other symptoms include:
- Irregular heartbeat
- Chest pain
- Being short of breath
- Feeling dizzy or lightheaded
- Feeling cold in extremities (hands and feet)
- Pale and/or yellow skin
- Cognitive difficulties, including lack of focus and attention
The newly discovered genetic link between anemia and insomnia
Several studies released over the past few years have explored the genetic underpinnings of insomnia, by conducting a genome-wide analyses to identify genes associated with insomnia complaints. This research found a particular gene,MEIS1, is strongly associated with insomnia.
This same gene is also associated with iron-deficiency anemia. The MEIS1 gene is involved in the metabolism of iron in the body.
The MEIS1 gene had already been linked to restless legs syndrome, a neurological condition that can have significant impact on sleep. In restless legs syndrome, or RLS, people experience a powerful urge to move their legs (also, sometimes their arms and/or the trunk of their bodies). This urge to move is accompanied by uncomfortable tingling and crawling sensations in the legs. These hallmark symptoms of RLS occur more often when we’re not being active—when we are sitting or lying down. (Being physically active tends to relieve the symptoms, for as long as the activity continues.) RLS symptoms are much more likely to occur, and intensify, at night. For these reasons, RLS can cause major disruptions to nightly rest, making it difficult to fall asleep and to remain asleep throughout the night.
People with low-iron levels—in particular, people with low-levels of iron in the brain, are significantly more likely to have RLS. Iron deficiency is considered a significant—and under-recognized—cause of this sleep disorder.
Identifying common genetic components for these conditions is tremendously important. It highlights the need for MORE research into the relationship between iron-deficiency anemia and sleep. It also provides us with a stronger understanding of the full spectrum of risks that contribute to anemia and sleep problems, and, potentially, a new way to identify and treat both iron-deficiency and sleep disorders more effectively.
Anemia and the risk for insomnia
The research into the relationship between iron-deficiency and insomnia in adults has been relatively limited. A handful of studies have demonstrated an association between iron-deficiency anemia and disrupted sleep, but we’re still in the early stages of understanding the impact that iron-deficiency has on adult sleep. Most of the research on the relationship between iron-deficiency and sleep has focused on restless legs syndrome.
Prompted by the discovery of the common gene linked to both conditions, scientists in China undertook a large-scale study to investigate whether having anemia elevates risk for insomnia. This study was conducted with data from more than 10,000 individuals, whose iron levels and other health markers were measured every 2 years, over a 6-year period. At the 6-year mark, participants underwent a sleep assessment for insomnia, which included information about sleep duration, sleep quality, ability to fall asleep, nighttime awakenings, waking early in the morning, daytime sleepiness, and daily functioning.
In their analysis, the researchers controlled for a broad range of non-anemia factors that can elevate risk for insomnia, including age, physical activity, smoking and alcohol consumption, BMI, and the presence of other health conditions including high blood pressure, high cholesterol, and diabetes. They found that among the study population, 4.3% had anemia and 15.2% had insomnia. And researchers identified several important connections between the two conditions:
- People who had previously been identified as having anemia had a higher prevalence of insomnia
- The presence of prior anemia was associated with a 32% greater risk of developing insomnia six years later
- Severe anemia was strongly linked to increased risk for insomnia. Mild and moderate anemia was also associated with an elevated insomnia risk, but to a lesser degree.
- Men with anemia were found to be at greater risk for insomnia than women with anemia
There’s more for us to learn here, to understand how anemia may contribute to insomnia, and how genetics may play a role in both conditions. But this new research suggests several important implications for insomnia treatment:
People with chronic insomnia, and their physicians, may need to consider iron-deficiency as a possible factor in their sleep problems.
Treatment for anemia ought to be conducted with an awareness of the potentially higher risk for insomnia.
More research is needed to understand how iron-deficiency contributes to sleep disruption, and how increasing iron levels through supplementation and diet modifications might improve sleep
What you can do
If you’re experiencing symptoms of chronic insomnia—trouble falling asleep, difficulty staying asleep through the night, waking very early, or waking feeling unrefreshed, for more than a month—talk with your doctor. There are steps we can all take in our own lives to improve our sleep, but it’s critical to address a sleep disorder such as insomnia in consultation with your physician and, ideally, a sleep specialist. (Here is where you can find an American Academy of Sleep Medicine accredited sleep center.)
The same guidance applies to any concerns you have about anemia, and your iron levels. Make an appointment to see your doctor and get tested. If you are anemic and you’re experiencing troubles with your sleep, talk with your doctor about how your anemia may be affecting your nightly rest.
There’s a lot of overlap between an iron-fortifying diet and a sleep-supportive diet. Many iron-rich foods, which can help maintain healthy iron levels, are also healthy choices for sleep. Dark leafy greens, nuts and seeds, legumes, and grass-fed meats are potent iron sources that all have a place in a sleep-friendly diet. Many of the fish that contain sleep-supporting omega-3 fatty acids are also rich in iron.
Michael J. Breus, PhD, DABSM
The Sleep Doctor™