Summarize the following:
Your parents may not realize sleepovers can be important when it comes to growth and development. Explain to your parents the potential benefits in allowing you to attend a sleepover.  Sleepovers build confidence. They force you out of your regular comfort zone and allow you to experience customs different than your own. A sleepover is also a practice in manners and respect. You'll have to learn to be courteous of the rules and regulations of another person's home. Attending a sleepover can help you learn to be a good guest. Say something like, "I think it would be good for me to experience new things. A sleepover can teach me to be a good guest."  Sleepovers allow kids to build social skills. Interacting with other children or teens your age is important to your growth. It also teaches more independence as you'll be able to experience things outside the context of your parents' home. Say something like, "I love spending time with you guys, but I'd like to have spend time with people my own age as well." It can sometimes help to compromise if you want to convince your parents to say "yes." For example, you can agree to call or text your parents every few hours to let them know you're okay. This might make them feel safer about allowing you to go as they'll have occasional assurance that you're okay. If you have a serious allergy, illness, or chronic condition that requires treatment, like asthma, bring up this topic before your parents do. Tell them how you plan to address such concerns at a slumber party.  Answering objections before parents bring them up can be the difference between “yes” and “no.” Countering potential arguments is a powerful in any negotiation and your talk with your parents is no different.  Role playing what you might do in a situation your parents fear can make them more relaxed. An example of this might look like:  Son: So, I'm a little worried about if I eat peanuts. Dad: Me too. You've had some bad allergic reactions in the past. What will you do if that happens? Son: Well, I've packed my EpiPen in my overnight bag and I told his mom I'm allergic, so I think I'll be OK. Your parents will likely be concerned about where you'll be. Provide contact information for the parents hosting the sleepover. If you provide information about where you'll be and how to contact you in the event of an emergency, your parents will be more likely to allow you to attend.

Summary:
Point out the benefits of sleepovers. Compromise. Talk about your medical concerns. Provide contact details.