Hello, Your sister is experiencing numbness and fainting spells. She is feeling tired / fatigued and goes off to sleep for hours. Your sister is suggested to get clinically examined by a GP, get all routine tests and investigations done to detect the pathology causing her such discomfort. Such symptoms may be indicative of anemia, poor general health condition, thyroid dysfunction, weakness, neurological problems, vitamin deficiency, dehydration, sudden drop of blood pressure or blood sugar, vasovagal syncope, etc. Your sister is suggested to take rest for a couple of days. Stay away from anxiety and stress. Stay well hydrated so that the body electrolyte system functions well, take home made nutritious food rich in minerals and protein. She should avoid skipping meals, stay active and avoid the use of alcohol, marijuana or illegal drugs, etc. as they may cause the worsening of the symptoms. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician