Almost Always Feel Sick After Sleeping (very Exceptional When I

almost always feel sick after sleeping (very exceptional when I don't). A night's sleep is not that bad, but naps (short or long) make me feel sick when I get up. I'm so tired I can't stay awake, but when I wake up I feel nauseous, overall bad uncomfortable feeling (waking up without alarm). Mostly lasts for the rest of the day when I slept during daytime.