The Elder Scrolls IV: Oblivion/Being a Vampire

In your adventure you will meet many vampires and you may receive the "porphyric hemophilia" disease from them while you're fighting with them. You can cure it with either a spell/potion cure disease or using an altar in a church

If you don't cure the disease within 3 days, when you sleep you will slowly become a vampire. This change is irreversible after you sleep and will take some time to clear up as it involves a quest

On the first day after you get the disease and you waste 24 hours and go to sleep for 1 hour you will receive these effects
 * Strength,Willpower and Speed go up 5points
 * Acrobatics, Athletics, Destruction, Hand-to-Hand, Illusion, Mysticism and Sneak skills go up 5 points
 * Resist Disease and Resist Paralysis 100%
 * Resist Normal Weapons 5%
 * Receive "Hunter sight" (combination of Night Eye and Detect life) Duration: 30 seconds
 * Weakness to fire 20%

If you waste 24 hours and sleep for 1 hour again you will get these effects:
 * Strength,Willpower and Speed go up 5points
 * Normal Weapon Resist 10%
 * Receive "Vampire's Seduction"+disposition(charm)50point for 20secs once a day
 * Sun Weakness:receive 1point damage every 1sec while outside in sunlight
 * Weakness to fire 30%

If you waste 24 hours and sleep for 1 hour for the third time you will get these effects: ->Strength,Willpower and Speed go up 5points ->Normal Weapon Resist 15% ->Receive "Reign of Terror"stop enemy from using spell and make lv6 or lower scare for 60sec use once a day ->Sun Weakness: receive 4 points of damage for every 1 sec while outside in sunlight ->Weakness to fire 40%

If you waste 24 hours and sleep for 1 hour for the fourth time you will get these effects:
 * Strength,Willpower and Speed go up 5points
 * Normal Weapon Resist 20%
 * Receive "Embrace of Shadows"Night Eye 90secs Invisibility120sec
 * Sun Weakness:receive 8point damage every 1sec while outside in sunlight
 * Weakness to fire 50%

A Vampire Cure
To start, you will need to talk to a priest or Vincente Valtieri of the dark brotherhood, it is best to talk to them both if you can as after you finish the quest you can still ask for a cure from Vicente even though you have cured it, making an uncompletable quest.