Is the fluid discharged during sleep considered semen, regardless of whether it was discharged discontinuously due to an attempt to prevent it or if it was naturally discharged discontinuously?

There is no difference between a little or a lot of semen. The emission of semen necessitates ghusl, whether it is a small or large amount, and whether it occurs during sleep or wakefulness. This is based on Al-Nawawi's statement: "Whether a large or small amount is emitted, even if it is part of a drop... all of that necessitates ghusl according to us." The Permanent Committee has also issued a fatwa stating that the forceful emission of semen due to desire necessitates ghusl, even if it is a single drop.