From www.briskodesh.org on the seriousness of spilling seed, according to Kabbala.
- Just like a person creates children through intercourse, so too, souls are drawn down every time a person spills seed.
- These souls are immediately captured by the forces of evil who torture and starve them, stealing all their energy for themselves.
- The souls brought down through a person's sins are also considered his kids.
- They are not to happy about the position their father put them in.
- After a person dies these souls come to take revenge on their father, causing him many problems (there are a number of halochos during the funeral and shivah that help prevent this).
- In addition, they also come after his physical children and try to harm them.
- Using energy taken from this person, the forces of darkness give birth to Lilim (sexual demons).
- These demons hang around a person, steal his energy, confuse him and stick thoughts in his head.
- If he tries to meditate, he will see many thoughts streaming through his mind are not his own.
- These thoughts include sexual thoughts and thoughts denying G-D.
- At night, these demons influence the persons dreams, and cause him to have nocturnal emissions (mikreh lailah).