Mood and energy do not live in a vacuum. Thyroid function and other hormones can nudge how you feel day to day. If you are noticing low mood, anxiety, brain fog, or a change in drive, it can be helpful to look at both mental health factors and the biology that supports them. This guide explains the big picture in plain language and shows when testing or treatment might make sense.

The quick take

  • An underactive thyroid often travels with low mood and fatigue, while an overactive thyroid can look like anxiety, irritability, and sleep trouble. Treating the thyroid problem often helps the mood problem. (Mayo Clinic)
  • Simple blood tests, usually TSH and free T4, are the starting point when a thyroid issue is suspected. Biotin supplements can throw these tests off, so pause biotin before labs if your clinician advises. (American Thyroid Association)
  • Hormone shifts outside the thyroid also matter. Perimenopause can raise the risk of depression, and true testosterone deficiency in men can affect mood and energy, though testosterone therapy is only for men with proven low levels and symptoms. (ACOG)

Thyroid basics and why mood can change

Your thyroid makes hormones that set the pace for many body systems. Too little slows things down. Too much speeds things up. When the pace is off, mood and thinking often follow.

  • Hypothyroidism can bring low mood, unusual tiredness, slowed thinking, and feeling flat.
  • Hyperthyroidism can bring anxiety, nervousness, irritability, restlessness, and trouble sleeping.

In general, the more severe the thyroid problem, the more noticeable the mood changes. Mood symptoms by themselves are not usually the only sign of thyroid disease, which is why a full checkup is important. (Mayo Clinic)

When to consider a thyroid check

Ask about testing if mood changes come with other thyroid clues such as weight change, sensitivity to cold or heat, bowel changes, tremor, neck fullness, or changes in hair and skin. Your clinician may order TSH and free T4 first and add other tests if needed. TSH is a sensitive gauge of underactive thyroid, while free T4 helps confirm how much hormone is available to your body. (aace.com)

Pro tip about biotin: Biotin, a common hair and nail supplement, can make thyroid tests look abnormal when your thyroid is actually fine. Many labs and thyroid groups advise pausing biotin for at least two days before bloodwork to reduce this interference. Tell your clinician about any supplements you take. (American Thyroid Association)

Medicines and the thyroid

Some psychiatric medicines interact with thyroid health. A well known example is lithium, which can increase the risk of goiter and hypothyroidism. Good care simply means monitoring thyroid labs at regular intervals and treating any thyroid change while continuing to support mood. (Psychiatry UW)

Beyond the thyroid: other hormones that influence mood

Perimenopause and menopause

Hormone fluctuations during the menopause transition can raise the risk of depression for some women. Anxiety can increase as well, and sleep disruption often makes symptoms worse. The good news is that these changes are treatable, and a plan that covers sleep, stress, therapy, and when appropriate medication or hormone therapy can help you feel more like yourself. (ACOG)

You do not need to wait until symptoms are severe. If low mood, irritability, brain fog, or night sweats are getting in the way of daily life, talk with your clinician about options.

Pregnancy, postpartum, and mood

Mood symptoms can begin during pregnancy or after delivery. Perinatal depression is common and treatable, and prompt support helps both parent and baby. If you also have a known thyroid condition, make sure your care team is coordinating because thyroid needs often change during and after pregnancy. If you are in crisis, call or text 988 for immediate help. (NIMH)

Testosterone and mood in men

Low testosterone can contribute to low energy, decreased drive, and low mood. Treatment is not a shortcut for sadness or fatigue, though. Professional societies recommend testosterone therapy only for men with consistent symptoms and repeatedly low testosterone levels, with regular monitoring once therapy starts. Your clinician can help decide if testing is warranted. (Endocrine)

What your visit might include

  1. Conversation and history. We listen first. We ask about mood, anxiety, sleep, energy, focus, menstrual or sexual health history, and family history.
  2. Targeted examination. We look for physical signs of thyroid or hormone change.
  3. Lab testing when indicated. Often TSH and free T4, and sometimes thyroid antibodies or other labs based on your story. If medicines like lithium are part of your plan, we include scheduled thyroid monitoring. (Psychiatry UW)
  4. A clear plan. If a thyroid or hormone issue is present, we outline treatment and follow up. If thyroid function is normal, we keep working on the mental health plan that fits your goals.

How treatment choices affect mood

  • Treating hypothyroidism with the right dose of thyroid hormone can lift energy and improve mood over time.
  • Treating hyperthyroidism calms the body’s pace, which can reduce anxiety and irritability.
  • Adjusting psychiatric medication can help when side effects or interactions are part of the picture.
  • Therapy, sleep, nutrition, and movement remain central, since biology and lifestyle work together.

Because every plan is personal, we make changes steadily and review how you feel at each step.

Practical steps you can take now

  • Keep a simple symptom log for two weeks that tracks sleep, mood, energy, and notable physical changes.
  • Bring a list of prescriptions and supplements to your visit. Include biotin if you take it. (American Thyroid Association)
  • If you take lithium, ask when your next thyroid lab check is due. (Psychiatry UW)
  • If you are approaching menopause and noticing mood changes or poor sleep, mention this directly at your next visit. (ACOG)

When to seek help sooner

  • Thoughts of self harm or a plan to hurt yourself
  • Severe anxiety, agitation, or confusion
  • Signs of a severe thyroid problem such as chest pain or shortness of breath

For life threatening emergencies call 911. For immediate mental health support call or text 988 to reach the Suicide and Crisis Lifeline, which is available every day at all hours. (SAMHSA)

The bottom line

Thyroid and other hormones can act like the backdrop to your mood. When that backdrop shifts, feelings and focus can shift too. The right testing and a coordinated plan can bring clarity. If you are ready to sort things out, schedule a visit at our Cookeville or Crossville office. We will listen first, check what needs checking, and tailor a plan that helps you move forward.

Educational content only. This article is not a substitute for medical advice. Always talk with your clinician before making changes to medication or supplements.