Many. There are many causes to fatigue and it's impossible to know what's the cause without lab works, physical exam and asking you about other symptoms. It could be anything: obstructive sleep apnea, anemia, thyroid, adrenal problems, infection, malabsorption, metabolic diseases, depression, stress....Please see your doctor to get this evaluated. I wish you luck!
Low iron? Other? Fatigue is a nonspecific symptom, meaning lots of things can cause it. Don't know your gender, age, etc. Iron deficiency is common in women of childbearing age, heavy periods, etc. Underactive thyroid common cause. Chronic infections including hepatitis, inflammation including autoimmune diseases depression. Meds. Sleep apnea other causes; adrenal insufficiency uncommon see your doc.
Adrenals. We tend to deplete adrenals due to constant stress, lack of sleep, minerals and water - take adhs (vasopressin) which is an adaptogen that resets adrenals 2tabs i'n the morning to release fatique.