If you have ever been conscious, but unable to move your body or speak when waking up or falling asleep, you have experienced sleep paralysis. During the so-called episode or attack, the person is able to open their eyes and is aware that he or she cannot move. Most occur when lying in a bed and when lying on your back.
If you look all over the web to find sources on this, there isn’t really a reliable definition. By reliable, I would mean that cherophobia is cited in a scholarly review paper. The closest to a medical diagnosis is from rightdiagnosis.com here. It defines cherophobia as ‘An exaggerated or irrational fear of gaiety or happiness.’ It too doesn’t provide a lot of details into the condition. However, another source here did talk about it more. Apparently, this condition may have occurred because of past disappointments. To me, this makes sense, because what else could possibly make a person afraid of being happy?