Opportunistic infections (OIs) are infections that occur more frequently and are more severe in individuals with weakened immune systems, including people with HIV.
Being nostalgic means to miss the past time. It seems that a real life was in the past because now in the present is different, probably things changed and we know that never is going to be the same. It leads to a nostalgic feeling.
Answer Wiki. Feeling sleepy is a message from your own body send to your mind. In translation - we need down time, so I (body) can do my maintenance task properly. It could be anything, but most likely it is generating vital energy. Tiredness is a physical stage after mental, emotional or physical action.