Does nightfall affect on muscle gain??

No: Nocturnal emissions (of semen) are normal for human males. If too worried, a primary care doctor or urologist can evaluate to see if the emissions are unusual (such as too often, too much semen, wrong age group, etc...) and decide if there is a problem. Meanwhile, one can choose some soft, absorbent underwear.

Nocturnal Emissions: are normal, especially in younger males. Please see your doctor to make sure all is well. When we feel something is out of our conscious control we may worry unnecessarily. Peace and good health.