I never sweat usually, but last night i sweat profusely and kept waking up to remove the covers & fan. my shirt & sheet became damp. is this serious?

Night sweats: Night sweats can occur with fever,taking medications like aspirin or Advil, hormonal disorders, various infections, exposure to excessive heat,or malignancies like lymphoma. At this time your sweats are nonspecific. Check your temperature, look for infection symptoms like sore throat, urinary burning,etc. See your physician if sweats persist or as needed if other symptoms develop.