Once, it was believed that masturbation was a sign of mental issues or perversion. Now, with the development of general healthcare and sex education specifically, masturbation is considered to be a healthy, safe and acceptable sexual activity.

Here are some of the main health benefits of masturbation

1. increases blood flow throughout your body; 
2. releases endorphins that influence your mood and well-being;
3. helps women during the menopause;  
4. increases the ability to have orgasms;
5. Improves sleep;
6. reduces stress;
7. relieves period cramps;
8. strengthens your muscle tone in the rectal and pelvic areas; 
9. decreases the risk of urinary tract infections by helping old bacteria to be flushed from the cervix.

Sources:

Are there side effects to masturbation?, medicalnewstoday.com

everydayhealth.com

A Touchy Subject: The Health Benefits of Masturbation, psychologytoday.com