Is there a link between hypothyroidism and insomnia?

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There may be a link between hypothyroidism and insomnia. A 2019 study explored the relationship between subclinical hypothyroidism and sleep quality.

Subclinical hypothyroidism is an early, mild form of the condition that does not meet the criteria for an official hypothyroidism diagnosis.

After comparing the sleep of 2,224 people who had subclinical hypothyroidism with 12,622 individuals who had healthy thyroid hormone levels, the authors found several correlations. In general, those with subclinical hypothyroidism had:

• shorter sleep duration
• longer sleep latency, which is the amount of time it takes to go to sleep
• lower satisfaction with sleep quality

The researchers also found that those with both subclinical hypothyroidism and low sleep quality were more likely to be female, be a younger age, or have a low body weight.

Older research from 2014 also looked at the possible connection between subclinical hypothyroidism and low-quality sleep, but the sample size was smaller and less diverse. The participants included 682 males, 38 of whom had hypothyroidism.

Analysis of the data revealed no association between thyroid hormone levels and low-quality sleep. However, because of the limitations of this study, it may not be accurate.

Subclinical hypothyroidism involves elevated levels of thyroid-stimulating hormone (TSH). When thyroid levels in the body are low, the part of the brain called the hypothalamus causes the pituitary gland to release more TSH.

When TSH reaches the thyroid gland, it stimulates the gland to make more of the hormone known as free thyroxine (T4).

People with subclinical hypothyroidism therefore have typical T4 levels in the blood and elevated TSH levels, which can mean they have absent or mild hypothyroidism symptoms.

Researchers do not fully understand how higher TSH levels may result in improper sleep, but they offer a possible theory.

This connection between the hypothalamus, pituitary gland, and thyroid gland is the hypothalamic-pituitary-thyroid (HPT) axis. As a person drifts off to sleep, the HPT axis becomes more active.

This increases the release of TSH, which stimulates the thyroid gland. Under certain physiological conditions, this thyroid stimulation may cause sleep difficulties.

While it is unknown if hypothyroidism can directly cause insomnia, it is possible for the condition to disrupt sleep indirectly. A person with hypothyroidism may experience:

Physical discomfort

The physical symptoms of hypothyroidism can sometimes disturb a person’s sleep. For example, if a person experiences joint or muscle pain, sensitivity to the cold, or anxiety, they may find it difficult to sleep.

An older 2011 study indicates that insomnia is more prevalent in people who have a higher number of medical conditions. With this in mind, the wide spectrum of symptoms hypothyroidism produces can have a negative influence on the quality of sleep.

Medication side effects

Doctors treat hypothyroidism with thyroxine, which boosts low levels of thyroid hormones to relieve the symptoms of the condition. At the correct dose, it is an effective treatment for many people.

However, if someone is taking more than they need, they can experience side effects, including:

• inability to sleep
• anxiety or nervousness
• increased appetite
• feeling hot
• shakiness
• racing heartbeat

Other health conditions

Hypothyroidism is associated with other health conditions that can disrupt sleep, such as obstructive sleep apnea (OSA), which causes breathing to temporarily stop and start repeatedly throughout the night.

OSA can cause daytime tiredness, frequent waking, or trouble staying asleep. Others sleeping in the same room may notice heavy snoring, choking, or gasping noises if someone has OSA.

Hypothyroidism is also associated with the symptoms of restless legs syndrome, which causes unpleasant crawling or tingling sensations in the legs when someone is resting.

What helps with insomnia depends on what is causing it. For those with hypothyroidism, a doctor may suggest:

• beginning thyroxine treatment to relieve physical discomfort
• lowering the dose of someone’s thyroxine to a more comfortable level if they are having side effects
• testing for other conditions that may be causing insomnia

It is important to not raise or lower the dose of thyroxine without speaking with a doctor first.

If starting or adjusting someone’s thyroid medication does not help, a doctor may look into other potential causes. They may ask someone about when their insomnia began, how often it occurs, and any changes that happened in their life around that time.

If a doctor suspects a sleep disorder such as OSA, they may refer the individual for a sleep study to diagnose it. Alternatively, if the insomnia is associated with another physical or mental health condition, the person may begin treatment for that.

Hypothyroidism does not have a cure, but in almost every case, medication can manage it, bringing thyroid hormones to a healthy level.

Evidence suggests that there are additional ways people can support their thyroid hormone levels, such as with:

Exercise

Older research from 2015 evaluated the effect of a regular physical exercise program in 20 individuals receiving treatment for hypothyroidism. The authors conducted blood tests for thyroid hormones before and after 3 months of daily 1-hour exercise sessions.

After comparing the results with people who did not engage in physical activity at all, they concluded that exercise can improve thyroid function.

Diet

Iodine is a nutrient that the thyroid gland uses to make thyroid hormones. Most people in the United States get enough iodine.

However, in rare cases, having an iodine deficiency can cause hypothyroidism. People with an iodine deficiency can get more of this substance from foods such as seaweed or from supplements.

If iodine deficiency is not the cause, taking iodine supplements will provide no benefit.

Additionally, people with autoimmune thyroid disease, such as Hashimoto’s disease, may find that iodine in food or supplements makes the condition worse. A doctor or dietitian will be able to advise on the best approach for each individual.

Something that almost anyone can benefit from is a diet that lowers inflammation. According to the U.S. Department of Veterans Affairs, inflammation is linked to a number of chronic conditions, including autoimmune thyroiditis. Thyroiditis may lead to hypothyroidism.

People with autoimmune hypothyroidism may benefit from an anti-inflammatory diet. This involves eating:

• plenty of fresh fruits, vegetables, and whole grains
• at least 30 grams of fiber per day
• foods that contain omega-3 fatty acids, such as wild salmon
• monounsaturated or “healthy” fats, such as olive oil, rather than saturated fat

Melatonin is a hormone the body naturally produces as part of the sleep-wake cycle. Its production increases with evening darkness, promoting healthy sleep, and stops when a person is exposed to light, helping them wake up.

As a result, it synchronizes the sleep-wake cycle with the rhythm of night and day.

Some people take additional melatonin as a sleep aid. According to the National Institutes of Health, short-term use of melatonin supplements appears to be safe, but very little research exists on the long-term effects.

A small study from 2001 looked at the effect of melatonin on females with hypothyroidism, 36 of whom were perimenopausal and 18 were postmenopausal. Researchers sorted the participants at random into two groups. One group took a placebo at bedtime, while the other took melatonin.

The scientists found that the group taking melatonin showed significantly higher levels of thyroid hormones compared with the placebo group after 3–6 months.

They suggested that low levels of melatonin due to aging may be connected with low levels of thyroid hormones, explaining why taking a melatonin supplement also improved TSH levels.

Large-scale trials are necessary to confirm melatonin is safe and effective for people with hypothyroidism. People who want to try a melatonin supplement should ask a doctor about safe dosages and be aware that supplements can vary significantly in quality.

Many factors can contribute to insomnia, including:

• stress
• shift work
• hormone changes, such as during pregnancy or menopause
• lifestyle factors, such as:
  • using electronic devices close to bedtime
  • exercising too little
  • using caffeine, nicotine, illegal drugs, or alcohol
  • taking long naps in the day
  • having an irregular sleep schedule
• environmental factors, such as:
  • noise or light
  • frequent travel to different time zones
  • a temperature that is too hot or cool in the bedroom

People experiencing sleep difficulties may benefit from reducing any of the possible risk factors for insomnia that they can control. For example, it can help to:

• create a cool, dark, and comfortable sleep environment
• wake up and go to bed at the same time every day
• reduce or stop caffeine and alcohol consumption
• quit smoking
• get regular exercise, while avoiding exercise in the evening before sleep
• manage stress or practice relaxation techniques

Hypothyroidism may be linked to insomnia, but the research so far is not consistent.

However, people with hypothyroidism often experience trouble tolerating cold temperatures at night or joint and muscle pain that can disrupt sleep. Side effects of thyroxine can also cause difficulty sleeping if the dose is too high.

Even if thyroid hormone deficiency is not directly causing insomnia, the wide range of symptoms associated with thyroid dysfunction can easily worsen sleeping difficulties and reduce a person’s ability to achieve quality, restful sleep.

Speak with a doctor if insomnia becomes a persistent problem. Treating the underlying problem and making lifestyle changes to promote sleep may help.