After the aberrant spirit entered your body, the mortal shell's very biology and mind were irrevocably altered and touched by something inhuman.

The normal digestive system and neural tissue have been altered to the point where regular mortal bodily needs are no longer necessary.

You are now able to survive off nothing but your own mind's energy. Food and water are no longer necessities.

Your body is no longer capable of sleeping; instead, you can rest by entering a 4-hour meditative state in which you can still perform light relaxing activities such as drawing, reading, or contemplating the day.

After resting in this way, you gain the same benefit as a human would from 8 hours of sleep.

Additionally, as your physiology has become more abnormal, you gain +1 to your constitution as your body becomes altered and your vital organs are shifted and "improved".