Typically veins are generally wider than arteries, and therefore the pressure is lower. Capillaries are tiny vessels, so repsent high resistance to the incoming blood, so the rate of blood flow through will be quite low. All blood from the artery eventually passes through capillaries and into the vein.
Other causes of an overactive thyroid can include inflammation of the thyroid due to viruses or bacterial infections. Also, postpartum hyperthyroidism affects women immediately after pregnancy. This is one of the most common postpartum health disorders, and it affects between ten and twenty percent of women.
Thyroid disease. An overactive thyroid gland (hyperthyroidism) can cause sleep problems. The disorder overstimulates the nervous system, making it hard to fall asleep, and it may cause night sweats, leading to nighttime arousals. Feeling cold and sleepy is a hallmark of an underactive thyroid (hypothyroidism).