Is the pleasure experienced during sleep and wet dreams the same as the pleasure that necessitates ghusl in a waking state? And is it permissible not to perform ghusl if the usual pleasure is not experienced in a wet dream, even if something that resembles semen is discharged?

What the questioner feels by way of pulsation and movement, not followed by enervation, is what is called minor pleasure (al-ladhdhah al-sughra). This is caused by foreplay or by thinking about things that arouse desire, and what is discharged as a result is madhi (pre-seminal fluid), not mani (seminal fluid). To cure waswas (obsessive whisperings), the questioner is advised to ignore them and pay no attention to them, to avoid inspecting the private parts, to perform istinja’ (ritual cleansing) upon waking up, to smell the hand and clothes, and to make abundant supplications.