National Sleepover Day is celebrated worldwide on May 9 every year, honoring the tradition of sleepovers, which are social gatherings where children and teenagers spend the night at a friend's house. This holiday, launched in 2017 by beauty brands bareMinerals and Sephora, along with Cosmopolitan magazine and influencer Olivia Culpo, encourages spontaneous sleepovers and fosters friendship and self-expression. Activities at sleepovers often include watching movies, playing games, doing makeovers, and enjoying snacks. While primarily associated with youth, sleepovers are also beneficial for adults, providing a chance to relax and strengthen relationships. The event promotes the use of hashtags like #SleepInTheBare and #NationalSleepoverDay, encouraging participants to share their experiences.