My boyfriend sleeps with the tip of his penis inside me after sex. Is this normal? We will face sexual disorders? Sometimes I have severe headache in morning due to this.

It's safe, considering you both are disease-free. Also, you'd probably want to consider your birth control status. If you're using condoms, the penis can shrink and the condom can slip off, exposing you both to disease and you to becoming pregnant if his semen seeps into your vagina.

Me and my man have done this before and he usually goes soft and falls out of me after 20 minutes or so, when we get all sleepy. Plus eventually, you want to roll over into a different position. I would sometimes fall asleep in the cowgirl position with him inside of me and it's really nice and intimate to lay there and get sleepy as close as two humans can be. 

But your mileage may vary depending on how long your man stays hard.

Also, try to Understand how to prevent  Sexually Transmitted Disease to have a healthy life. 

Some ways to prevent STD's are:

• Use good condoms every time you have sex. If you use a lubricant, make sure it's water-based. Use condoms for the entire sex act. Condoms are not 100% effective at preventing disease or pregnancy. However, they are extremely effective if used properly. 
• Avoid sharing towels or underclothing.
• Wash your private place properly before and after intercourse.
• Get a vaccination for hepatitis B. This is a series of three shots.
• Get tested for HIV.
• If you have a problem with drug or alcohol abuse, get help. People who are drunk or on drugs often fail to have safe sex.
• Avoid having sex with multiple partners.

Always remember, Prevention is always better than cure. ❤️