For many of us, summer evokes memories of long days spent outdoors biking, swimming and playing in sprinklers. But for children who suffer from xeroderma pigmentosum and other photosensitivity disorders, summer can be the loneliest time of the year.

Sometimes understood as an allergy to the sun, XP is not actually an allergy but a rare genetic disorder that causes extreme sensitivity to sunlight, even after just a few minutes of exposure.

“Some patients said it was like… dipping their hand in boiling water, or being stabbed by 100 knives,” Dr. Manisha Balwani, Associate Professor of Genetics and Genomic Sciences at Mount Sinai Hospital, tells NBC News.

This inability to go outside for recess or play soccer after school can be very isolating for kids. But thanks to Camp Sundown in Craryville, New York, children suffering from these rare disorders don’t have to miss out on the classic summer camp experience.

Daniel and Caren Mahar founded Camp Sundown in 1995 after their daughter was diagnosed with photosensitivity. Since then, the camp continues to grow in attendance and raise awareness about XP and similar diseases.

During the day, campers stay inside in buildings outfitted with tinted windows and incandescent lights to prevent UV exposure. They make arts and crafts, watch movies and generally goof around like any group of kids would. By 9pm, they’re ready to run outside to go swimming and play sports. They sing songs around campfires and go stargazing in the quiet wilderness.

In 2016, Liza Mandelup created a short documentary showing what life is like Camp Sundown. While the schedule may be inverted, the experience will feel familiar to anyone who went away to camp and built bonds that felt like family. For these kids, camp is a sanctuary. It’s a safe place where their condition is understood. Most of all, it’s a home where they feel less alone in the dark.