Introduction:
Sleep is essential for good health and well-being. It helps an individual lead a good quality of life. Individuals spend around one-third of their lives in bed. Studies have found that abnormal sleep may lead to diseases like thrombotic disease, epilepsy, arthritis, mood disorders, chronic pain, and diabetes mellitus. Normal, quality sleep helps the body function properly. Good sleep is involved in regulating thyroid hormones.
What Is the Importance of Sleep?
Sleep is needed for life and proper function. It is considered complex and tightly connected to physiological regulation. Sleep is important for many brain functions, including nerve cell communication. Although it is a resting state, the body and the brain are active during sleep.
The recommended daily sleep is seven to nine hours per day. Many individuals suffer from sleep disorders. It is estimated that around 48 percent of American adults report a sleep duration within the recommended sleep range.
Studies have found that quality sleep is linked to the endocrine system's effects. It has been found that growth hormone (GH) and prolactin (PRL) levels increase in deep sleep. It was also noticed that there was a drop in cortisol and thyrotropin (TSH). Circadian rhythm changes with sleep disruption may affect the inflammatory system.
Many studies have found that a lack of or disrupted sleep may lead to health issues. Studies have observed a link between sleep duration and health issues like heart disease, mental disorders, and mortality (death).
How Sleep Is Linked to Thyroid Regulation?
The thyroid is a small gland located in the front of the neck. It produces two hormones: thyroxine (T4) and triiodothyronine (T3). The thyroid gland is a part of the endocrine system that regulates many bodily functions. The important function of the thyroid gland is to control the speed of metabolism (metabolic rate). Metabolism is the process by which food is converted into energy. All cells of the body need energy to function. If the thyroid gland does not function properly, it may affect the entire body.
The hormones secreted by the thyroid gland include
Thyroxine (T4): This is the main hormone produced by the thyroid gland. It does not have a role in the metabolism, but it gets converted into T3 in the bloodstream through deiodination.
Triiodothyronine (T3): This hormone is secreted in less quantity than T4. It plays a major role in the metabolism process.
Reverse Triiodothyronine (RT3): The thyroid secretes a small quantity of RT3. This hormone reverses the action of T3.
Calcitonin: This hormone is responsible for maintaining calcium levels in the blood.
The thyroid gland needs iodine to make hormones. Iodine is available through food and water. The thyroid absorbs iodine and helps prepare thyroid hormones. High and low levels of iodine may affect thyroid hormone production.
Thyroid hormones can affect many bodily functions. These include:
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Metabolism (process of how the body uses energy).
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Heart rate.
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Breathing.
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Digestion process.
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Regulates body temperature.
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Brain development.
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Maintenance of skin and bones.
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Mental activity.
A complex system of the body regulates thyroid hormones. The hypothalamus (a part of the brain) secretes thyroid-releasing hormone (TRH). This hormone stimulates the pituitary gland to release thyroid-stimulating hormone (TSH). TSH stimulates the thyroid follicular cells to release T4 and T3. The release of T4 and T3 requires adequate iodine in the body.
Thyroid hormone secretion and signaling play important roles in human growth and development. The hypothalamic-pituitary-thyroid (HPT) axis is responsible for the production and secretion of thyroid hormones. The HPT axis starts the production of thyroid hormones based on the signal in the hypothalamic paraventricular nucleus before the signal is transmitted through the pituitary and thyroid glands.
All hormones are produced in a cyclical rhythm over 24 hours. Sleep can influence the regulation of this rhythm. Sleep deviation can change the functioning of the human HPT axis. Sleep can impact TSH, T4, and T3.
A study found that sleep can impact the HPT axis based on sleep duration. A short-term sleep restriction can increase the levels of TSH, and T4. A long-term sleep restriction may decrease the levels of TSH and T4.
Sleep deprivation is considered very stressful for the affected person. Others generally disregard this condition. Thyroid problems such as hypothyroidism (underactive) and hyperthyroidism are linked to cause sleep issues. Hyperthyroidism occurs due to increased levels of thyroid hormones. This condition can cause difficulty sleeping. Difficulties sleeping include muscle weakness, irritability, nervousness, and continuous tiredness. Night sweats and frequent urination due to hyperthyroidism may lead to difficulty sleeping.
Hypothyroidism caused by decreased levels of thyroid hormones is associated with sleep problems. Individuals affected by hypothyroidism cannot tolerate colds at night times, and joint or muscle pain may lead to disturbances in sleep. Studies have found a link between hypothyroidism and poor quality sleep, time taken to fall asleep, and shorter sleeping hours in the night. This condition can be observed among younger individuals, especially women with a low body mass index (weight/height (square)). Hypothyroidism may lead to hypersomnia (excessive sleepiness).
Thyroid disease may cause restless leg syndrome (RLS). Affected individuals experience unpleasant sensations in their legs while the body is at rest. The symptoms of RLS start in the evening and during the onset of sleep, and this condition may result in significant sleep loss.
Hyperthyroidism may cause night terrors. Night terror is a type of sleep disorder in which sudden, terrified outbursts may occur. Abnormal sleep habits may lead to the development of thyroid problems.
A study has found that those who tend to sleep for fewer than seven hours may be at higher risk of being affected by hyperthyroidism. It was also observed that sleeping for more than eight hours may cause either hyperthyroidism or hypothyroidism. Hence, optimal sleep is important and helps the immune system function properly. Individuals with weaker immune systems are more likely to be affected by thyroid dysfunction.
Conclusion:
Sleep is a state of reduced mental and physical activity. A person needs to carry out functions effectively in the daytime. Many hormones are involved in this process. The thyroid is an endocrinal gland that regulates many important body functions. Studies have found an association between sleep and thyroid function regulation. Hence, knowing about sleep and its relation to thyroid function and disorders becomes important.
