My sons grew out of their beds and I didn’t notice.

Liam, 17, alerted me to this about a month ago, casually mentioning that he and Jacob no longer fit in their beds and wondering if they could get new ones.

“If we lay flat on our stomachs, our legs hang off the bed, starting around our shins,” Liam said. “But if we just curl up, then we kind of fit, so if you feel like it’s not worth the money, it’s OK.”

I was horrified by my inattention. The boys had had their bunk beds since Liam graduated from his crib and Jacob was in kindergarten. Somewhere in late middle school, when they started staying up later than me, I stopped tucking them in.

By the time Jacob started high school, we separated the bunks into twin beds. Their bedtimes extended even later as homework increased. Looking at Liam, I realized that, with the exception of poking my head into a darkened room when one of them overslept, I had not seen either boy in bed for years. And now they were both 6 feet-4 inches tall. Of course they didn’t fit in their childhood bunk beds.

The next weekend, my husband Bill and Liam went shopping and bought two extra-long twin beds. I bought some extra-long sheets online, and Liam dismantled the bunk beds.

Once I moved past the guilt of not noticing their growth, the nostalgia kicked in. Jacob and Liam slept in bassinettes as infants, white baskets on wheels that I would pull next to my side of the bed at night for easy access to feed them.

I so clearly remembered looking at the crib set up in baby Jacob’s room, untouched, waiting for him to outgrow the bassinette. I remember watching 3-month-old Jacob sleep in his bassinette, wondering if he was big enough for the crib yet, concerned that the bumper would adequately protect him if he’d roll.

How could it be that these boys were once so tiny I could carry them with one arm? Liam’s first car seat looked like a cradle with a handle. It clicked into a heavy plastic base. He was so small he needed a head-holder foam situation to keep his head from rolling off to the side, before he had the neck control to hold it up. Now that cradle car seat would barely hold both of Liam’s shoes.

They moved into bunk beds when toddler Teenasia arrived as a foster child. Teenasia got Liam’s crib and Liam moved to the bottom bunk. I had to stand on the ladder to kiss Jacob goodnight. Three small children in one room. In the morning, Teenasia would toss a stuffed animal into Liam’s bunk to wake him up. She was an athlete even then.

When Teenasia, at age 2, went back to her biological family, and Jamie came as a foster child, she received the vacated crib and the boys again had a sister as a roommate. When we adopted Jamie, Bill and I knew that two boys and a girl sharing a room wouldn’t work for long, and we moved to a larger house. The bunk beds moved too.

Dinosaur and race car sheets were replaced by solid colors or patterns as the boys outgrew the need to have smiling creatures or vehicles on their bedding. The crib converted to a toddler bed in Jamie’s room, and when Teenasia rejoined the family at 4, a friend shared her daughter’s outgrown princess dollhouse bed, with a pink shuttered window for a headboard.

Beds have significance in family life. They represent not only rest, but refuge. When Teenasia was placed back with her biological father at age 5, after being part of our family the second time, I gave that princess dollhouse bed away. It was too painful to look at it empty each night, and wonder if Teenasia even had a bed of her own where she was.

But the boys’ bunk beds, mission style and constructed of strong oak, were never empty. I suppose one reason I never discovered the beds were too small was maybe I didn’t quite want to admit that my sons were more young men than boys. Maybe I thought their height was a temporary condition and any second they’d go back to being the little boys I thought I’d always have.

After the purchase of new beds, I offered the bunks to colleagues at work and neighbors, but none of them needed them for their children.

Finally, I told Liam he could put the bunk beds on Craigslist. I didn’t love the idea of selling the beds to a stranger. I would rather have given them to someone I knew — someone whose kids I could watch grow up, knowing at night those kids were snuggled in the bunk beds.

But on Superbowl Sunday, three days after Jacob’s 21st birthday, Liam had a call for the bunk beds. I pulled into the driveway just as Liam was helping a woman load the bed frames into her SUV. She was in her late-20s and had a warm countenance about her.

“You’ll love these bunk beds,” I said. “Do you have kids?”

“Soon, I hope,” she said, sliding in the ladder. “I’m getting licensed to be a foster parent, so I’m hoping to have a sibling group by summer.”

I tried to blink back my tears, but failed.

My boys’ bunk beds were moving on, and I was glad that none of my friends needed them; glad they were going to this stranger. They had important work to do.

(Annemarie Scobey-Polacheck’s writing on faith and family life has won local and national awards. To see past columns, go to www.discoveringmotherhood.com.)