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Natural Awakenings Rhode Island

Natural Sleep Cycles

Oct 29, 2019 02:46PM ● By Maureen Cary
Natural 
Sleep Cycles
CIRCADIAN RHYTHM AND 
THYROID FUNCTION

by Kathleen Cannon

Our circadian rhythm relates to our body’s natural cycles of sleep and waking and changes throughout the year. Influenced by the environment in which we live, our circadian rhythm may make us more of a morning person or a night owl, and possibly increase our body’s need for rest during the darker months of the year. 

Largely governed by the pituitary gland, The HPT axis is the hypothalamic-pituitary-thryoid axis (similar to the HPA axis, where A stands for adrenal). The hypothalamus is located in the brain and sends signals to the pituitary gland, also located in the brain, which then signals the thyroid gland as well as other systems in the body. The thyroid gland does its work and sends feedback messages to both the hypothalamus and pituitary glands. This constant communication of the HPT axis is how the body regulates itself. 

Our circadian rhythm is governed by a part of the hypothalamus called the suprachiasmatic nucleus which also coordinates other physiological influences on circadian rhythm. As the hypothalamus is an important part of the HPT axis (and many other functions), the relationship between sleep and our thyroid is important to consider.

The thyroid gland influences a vast array of physiological functions, including digestion, psycho-emotional state, metabolism, reproductive health and more. Symptoms of low thyroid function, or hypothyroidism, can include fatigue, weight gain, hair loss, mood changes, fertility challenges, constipation and dry skin. Less common is overactive thyroid, or hyperthyroidism, where symptoms can include anxiety, weight loss and palpitations. 
Clinically, a strong relationship is seen between thyroid function and a person’s energy level. For many people dealing with fatigue, thyroid function comes into play.

Naturopathically, practitioners determine what is causing the thyroid to under-function while supporting the gland itself and the person’s symptom of fatigue (and usually more). It’s helpful to understand how to support the thyroid in the context of circadian rhythm, as it is part of the physiologic environment in which the thyroid gland functions. 

Research published at the National Institute of Health on the circadian system, sleep and endocrinology shows there is indeed a circadian rhythm to thyroid function. Interestingly, the levels of thyroid hormones themselves (T3 and T4) stay relatively stable throughout a typical 24-hour period. The level of thyroid stimulating hormone (TSH), which signals the thyroid to produce hormones, varies more; TSH is actually at its peak around midnight to 1 a.m., and at its lowest during the afternoon. It tends to rise in the evening, until midnight when it starts to dip, and then rises again around 6 a.m. or so, only to drop off significantly in the afternoon. Research has shown that when we go to bed, our TSH level tends to rise and then fall when we drift off to sleep; however, if we force ourselves to stay awake past our typical bedtime, our TSH will continue to be elevated until we go to sleep, at which point it will drop off—this can disrupt our body’s natural rhythm.

Due to the rise and fall of TSH levels, it is best to maintain a routine sleep-wake schedule. Go to bed around the same time every night and wake up around the same time every day. Consistency may help prevent variations related to circadian changes. Another takeaway: if and when thyroid testing is done, making sure every test is performed at about the same time of day may reduce fluctuations related to circadian rhythm.

An interesting note is that circadian rhythm is most affected by light—the intensity and type of light are important, too. Especially in cases of circadian rhythm disruption coupled with low mood in the winter related to seasonal affective disorder, ensuring adequate light exposure may be helpful. Certain types of indoor lights are available that mimic sunlight and help the body to wake up in the morning. These lights can be programmed to turn on before we wake up in the morning, as if the sun is rising. 

Dr. Kathleen Cannon is a naturopathic physician with a family practice located in Norwich, CT. For more information, visit DrKathleenCannon.com.