Sleepover guests prepare for bed at the Penguins + Pajamas overnight event at the California Academy of Sciences in San Francisco. (Kathryn Whitney/California Academy of Sciences)

Outside the California Academy of Sciences, children struggled under the weight of overstuffed backpacks, and parents tussled with bulky sleeping bags and pillows. I was traveling much lighter — a nylon sack with a toothbrush and sweatshirt — but I also carried a load on my shoulders.

My burden: Would I choose penguins over my best friend from childhood?

The line moved up an inch. Through the glass entrance, I noticed a stuffed toy penguin on the check-in desk. A telling sign.

Nearly once a month, the natural history museum in San Francisco’s Golden Gate Park transforms into a sleepover science camp. The Penguins + Pajamas event, now in its sixth year, starts after daytime visitors have departed and before most children’s meltdown hour. In addition to après-hour roaming privileges, slumber partiers can participate in special programs (including live animals) and camp out among the exhibits (ditto).

“Since the event takes place after normal hours, sleepover guests have a much more intimate museum experience,” said Kelly Mendez, a spokeswoman. “We hope they leave inspired by the natural world.”

Doors open at 6 p.m. However, a sentence in my confirmation letter — “sleep cards are handed out on a first come first serve basis for each area” — set off a warning bell. The museum offers five sleeping districts, and each has limited capacity. If I arrived too late, I could end up dozing with natural disasters (Earthquake) or an albino alligator (Lower Swamp) instead of with my preferred bedmates, African penguins (African Hall). In addition, the museum requires all members of your party to be present when selecting an area. The other members of my crew were wedged in traffic on the Golden Gate Bridge.

Kids sleep with the fish in the Aquarium, one of five slumber areas at the museum. (Kathryn Whitney/California Academy of Sciences)

I started polling other participants about their top two choices. A dad from Davis, Calif., whose son was splayed on a sleeping bag, said Aquarium and African Hall. I told him that I had heard that Aquarium was way cooler. I flagged down a staff member and asked him which sleeping chambers fill up first. He confirmed my fears.

I was all ready to sacrifice my friendship when I noticed two familiar faces by the T. rex in the lobby. Chrissy and Lindsay, my friend’s teenage daughter, had accidentally entered with a Boy Scout group and were checking in — swing goes the karma. An employee stamped our hands with an inky penguin. I pressed the backs of my hands together to make a pair.

We dropped off our gear in the African Hall, a temporary storage unit for the 300 guests that mid-November evening. I noticed a barrier separating the sleeping space from the habitat where 15 penguins resided.

“You can’t sleep up against the glass,” a staff member said. “You have to stay 20 feet away. They need space.”

I would give them their personal space, but not their privacy. I scanned the long, high-ceilinged room and located the spot with the closest penguin views: front-right corner, by the Hunter’s hartebeest. According to the schedule, we could set up our permanent settlement at 10 p.m. Till then, we would prowl the halls like a pack of nocturnal animals.

“It kind of feels like we’ve broken into a museum,” said Lindsay. “But that’s cool.”

We studied the list of activities and shouted out our favorites. Lindsay, a high school freshman in Marin County, Calif., was learning about the solar system and selected two planetarium shows. Chrissy chose the four-story rain forest, where she could face some of her phobias. I selected the Animal Color Encounter because, well, it was starting in five minutes.

In the Color of Life section, two staff members explained the concept of camouflage to a young, bouncy audience seated in bleachers. To illustrate their point, they produced a ball python as thick as a chunky scarf.

“The python uses its color to hide and eat mice,” the expert said. “How wide does his mouth open?”

Hands shot up, then approximated a maw that could fit a bowling ball.

Halfway through the talk, I looked around and realized that two-thirds of my group had wandered off. I found them by an exhibit featuring California newts. My friend, clearly alarmed, urged me to read the informational sign, which explained how the toxin in a single newt can kill thousands of mice.

“Why haven’t we heard about these?” she said in her protective mother voice.

We decided to look for critters with kinder dispositions.

En route to the rain forest, we passed a gaggle of dads tossing back bottles of beer.

“Is there a mom’s wine corner?” she asked.

(Yes, in the Academy Cafe, which has a stocked cooler of reds and whites.)

On average, upwards of 4,000 people visit the museum each day. Entering the rain forest can require significant time and patience. We, however, breezed right in, pausing only to consider the photographer’s question: “Do you want to take a penguin picture?” (Unfortunately, not a real bird but you in a penguin hat.)

We climbed the ramp, passing under a wireless mobile of butterflies. I peeked into glass boxes housing exotic creatures, such as Borneo gliders and golden mantellas, vibrant frogs from Madagascar that looked as if they had fallen into Benjamin Moore paint cans. Chrissy, meanwhile, was admiring a fluttery insect with a pair of trompe l’oeil eyes on its wings.

“I think I’m getting over my fear of moths,” she said. “This one is so pretty and peaceful.”

I didn’t have the heart to tell her that her breakthrough moment involved an owl butterfly, not a moth.

A few minutes shy of 8 p.m., the staff started to clear the ecosystem. Its inhabitants follow the same sleep schedules as fourth-graders.

“The animals in the rain forest have an early bedtime,” an employee said as we exited.

Before the first planetarium show, we ducked into the cafe for dinner. As a special treat, the kitchen staff allowed guests to make their own pizzas. A chef in a white coat invited me behind the counter and handed me plastic gloves, which I slipped on and plunged into bowls filled with olives, pineapple, spinach and zucchini. He seemed relaxed and good-humored, even as I was butchering flavors.

At “Tour of the Night Sky,” a jocular employee read a few announcements. He told us that we would have to stow all flashlights and electronics at night, so as not to disturb the animals. A couple of youngsters gasped, but he assured them that none of the sleep areas would be cave dark. He also informed us that we would have to rise at 6:30 a.m., which caused this adult to howl. We also had to vacate the museum by 8 a.m. so the “biologists can begin their work,” but we were welcome to return for free when the museum reopened later that morning.

Then the lights went down and the stars came up.

We learned about cosmic dust, or star dandruff, and that the Milky Way supposedly tastes like raspberries. We also viewed Orion, who “is a hunter, not a thinker.” Throughout the presentation, a chorus of kids would sing out, “Black hole!” The educator swatted away the interruptions, but I could feel Lindsay rolling her eyes to the heavens above.

Families set up camp in the African Hall, which is also home to the (live) African penguins. (Andrea Sachs/The Washington Post)

Bed assembly time was nearing. Chrissy ran down to the car to grab extra blankets, and Lindsay and I climbed to the rooftop to peer through a telescope at Capella, two polka dots on a velvet skirt. We arrived at the African Hall a few minutes before 10 p.m. An employee said we could sleep anywhere except under the tree with the leopard crouched on the top branch. A mother and her son had already nabbed the prime penguin spot. We walked through the gallery of dioramas, past a pride of lions, a pair of zebras and a cheetah hunting a Thomson’s gazelle. We stepped around sleeping bags, air mattresses and a low wall of rolling luggage. We finally found a space in the back, under an empty vitrine. The only consolation: I had an outlet within arm’s length.

For my evening ablutions, I went to the public bathroom and waited for a sink behind a girl in “Frozen” pajamas and a mom in yoga pants. Instead of heading right to bed, I crept downstairs to the aquarium, where rows of heads rested against tanks that glowed like lava lamps. I took the long route back. The California Academy of Sciences felt like my own private museum, and I wanted to prolong the fantasy.

In the African Hall, I tiptoed up to the penguins to say good night. Four birds stood like chess pieces, waiting for the next move. Eventually, the lights went out in their home, a signal that it was bedtime for all species.

Chrissy and Lindsay were fast asleep. I fluffed my blanket and pillow and closed my eyes. The room was silent until I heard a man trying to expel a warthog through his nose. The snoring was primal and penetrating. I jammed squishy earplugs, a gift from the museum, into my ears. Useless. I moved around the corner, cozying up with the African hunting dogs. I could still hear the loud snorts. I rolled up my bedding and embarked into the unknown. I walked over to Color of Life, but cocooned bodies occupied most of the nooks. Earthquake was too exposing; Aquarium was filled to capacity. I finally discovered a secluded corner shaded by two giraffes. I didn’t have to worry about the pair snoring; their noses were stuffed.

The author finds quiet quarters under the giraffes. (Andrea Sachs/The Washington Post)

Guests can sleep within viewing distance of the African penguins. But eventually, it’s lights out for all species. (Andrea Sachs/The Washington Post)

The staff woke us up with a cheery camp-counselor announcement to rise and shine. We packed up our belongings and ventured over to the cafe for breakfast. Chrissy grabbed a table by the spotted cuscus, and we discussed the overnight-at-the-museum experience.

“I had a really good sleep. The floor wasn’t as hard as I thought it would be,” Lindsay said, adding: “It’s funny that they call it sleeping with penguins. You’re really sleeping with the Academy of Sciences.”

Chrissy, who had been initially wary of the event, shared her epiphany.

“It’s not all about your comforts,” she said triumphantly. “This made me feel like I can go ahead with other adventures.”’

My friends left shortly thereafter. I stayed behind and returned to the African Hall, now cleared of last night’s evidence. I faced the penguins and watched them slowly come out to greet the new day.

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If you go
California Academy of Sciences

55 Music Concourse Dr.

Golden Gate Park, San Francisco


The Penguins + Pajamas sleepover is available to children ages 5 to 17, plus adult chaperones ages 25 and older. No adult-only groups allowed. The $109 nonmember fee includes an evening snack, breakfast, parking and museum admission the following day. You must bring your own sleeping gear. Upcoming dates: Feb. 12, May 27 and June 18.

— A.S.