Low Thyroid hormone can causes hair loss, sluggishness and low metabolic rate.
Lowered metabolic rateaccompanied by mental and physical sluggishness
Spark plugs could be a reason for sluggishness in your car. Other causes for sluggish starting are a poorly grounded starter, a bad fuel pressure regulator, corroded terminals on the cap and rotor or a faulty coil.
Hemostasis is the medical term that means stoppage or sluggishness of blood flow.
Lethargic. No energy, sluggishness, slowness or dullness. (No get up and go)
It means torpor, or lethargy, a state of sluggishness or lack of action.
Hashimoto's causes inflammation of the thyroid gland. It also causes the thyroid gland to become underactive, or hypothyroid. Symptoms of Hashimoto's are similar to hypothyroidism. This includes sluggishness, fatigue, weight gain, heat and cold intolerance, constipation, depression, menstrual and fertility issues
You could use the word 'turgid'...
Immobility, idleness, inertia, inactivity, sluggishness, laziness...
hypothyroidism
inadequate amounts of thyroid hormone
According to http://www.merriam-webster.com/thesaurus/speed antonyms to speed are slowness and sluggishness