A question I frequently hear myself asking these days is: “How late did you stay up?” Anyone with teens in the house isn’t surprised by this. Many teenagers, when schedules allow, like to stay up late and sleep in late. For them, it’s part of summer vacation – even if they can only get away with doing so a couple days a week.

I’ll suggest watching a movie at 7 p.m. My daughter and a cousin or friend sleeping over think that’s the middle of the afternoon. They’ll pop the popcorn into the microwave no earlier than 10 p.m. One night, I watched as they heated up some vegetable noodle soup even later than that. Our recent cool evenings put them in the mood for something warm to eat. It’s too bad they slept in too late the next day to see the early-morning dog walkers in our neighborhood wearing sweatshirts, as most were doing last week for an extra layer of warmth.

But I’m not talking only about the teenage girls under my watch. My mother, who loves to read, simply cannot put down a good book once she has started it. When I call her for my usual 9 a.m. daily check-in, I know immediately by her groggy hello that she has stayed up late again.

“Are you awake?” I’ll ask.

“I am now,” she’ll reply.

“How late did you stay up reading?” I’ll continue.

“I don’t know … 1, maybe later. Hold on; I have another call,” she’ll say.

It’s probably some book club member calling to ask her to join them, I joke to myself. Perhaps the club meets late in the evening, for her convenience.

Of course my mother – retired, relatively healthy and hooked on books – is free to stay up and read until dawn if she chooses. It’s not as if she is alone. She has Stuart Woods, James Patterson, Barbara Taylor Bradford, Mary Higgins Clark and her other favorite authors to keep her company.

She has a Nook but prefers the real deal. Through the years I have probably checked out hundreds of books from the library for her. I’ll enter her condo with a tall stack of them and she’ll look as if she has just won the lottery.

“Now I’ll never get any sleep,” she’ll laugh, reaching out to examine each book and deciding which one to read first.

She prefers the large-print versions. She’ll sit on top of her bed or under the covers with a book the size of a bread box, her reading glasses perched on her nose and a tall glass of ice water within reach on her bedside table. It’s important to keep hydrated when reading an action-packed thriller late at night, I suppose. I have witnessed this scene countless times, reassuring her that, yes, I’ll make sure her back door is locked when I leave. Then I’ll drive home and go to bed before 10 p.m.

Funny how things change through the years. When I was a teenager, I sometimes stayed up later than my parents – reading, studying, talking to friends on the phone, listening to the radio. In college I had friends who didn’t start studying some nights until 10 p.m. and avoided 8 a.m. classes whenever possible. Back then 10 p.m. was early to us but, for many, 8 a.m. was a nearly impossible hour to be awake.

Once I became a parent, for years I was awake several hours after my daughter went to bed. Oh for those nights of bedtime stories and 8 p.m. Lights Out! Now, at age 15, she is wide awake long after our last load of laundry has been done and the dog has had his final walk of the day.

You get to know people’s evening and bedtime schedules. I know the ones who eat dinner before 6 p.m. and those who eat after 7 p.m. I have friends and relatives I wouldn’t dream of calling after 8 p.m. – especially during the school year. Others are best to reach after 9:30 p.m.

Similarly, the sound of an 8 p.m. dinner reservation sounds late to me now – even though we did it for years. By that point in the evening, I’m already thinking about what to pack for lunch the next day.

And when I schedule a haircut for a Saturday, I book six weeks in advance so I can be sure to get the first appointment of the day. Why not? I’ve already been up for hours.

My daughter, on the other hand, prefers something after 11:30 a.m., please.

I realize that summer – especially summer vacation – is a good excuse to stay up late. Sleepovers, star-gazing, bonfires, evening walks, movie nights, relaxing with friends on the porch and, of course, late-night reading are only a few reasons to ignore the clock.

I read on the PBS website that allowing kids to stay up late reading under the covers once in a while is a good way to grow a bookworm. Like catching fireflies, eating ice cream and slamming screen doors, doing so is part of carving out a fun summer for kids.

As for the grown-ups, my mother is happy because her cousin recently passed along yet another book for her to read. My guess is that she is almost done with it. I’m sure the same is true with the latest stack I brought her from the public library.

She always tells me she has enough to read, though. She has some books on her shelves she wouldn’t mind diving into again until we stock her up.

And, she adds, she can always turn on the TCM channel – Turner Classic Movies. Oh, yes, another excuse for staying up late.