I remember the first time I realized my mother went to parenting classes. I thought that it was so funny. I mean, she was my mother. She knew everything, right? What did she need parenting classes for?

Well, I grew up, learned a little bit more,What can your newborn do? gained a broader perspective and had some kids of my own. And now I realize what a balancing act parenting is and how important it is for us to have some guidance.

As a kid, everything seems so straightforward. We know what our needs are, we know what our weaknesses and strengths are, and surely, our parents know them too, right? Wrong! (Sadly. It would be great if we always knew.)

One of the hardest parts of parenting is realizing what our children are capable of and what they’re not, especially when it comes to babies.

I remember when my twins (my first children) were newborns. I couldn’t do stairs, so we all just lived on the main floor of my two-story apartment during the day. There was really only one room for them to be in: the kitchen/living room/dining room. So that’s where they were.

And that’s where we were, too, with all the lights and noise and cooking smells bombarding them. They’d be up for hours at a time, and boy were they kvetchy! I called the nurse’s line at my pediatrician’s office, but she assured me that being awake for four hours at a time was normal. Hmm. Something sounded off to me.

What can your newborn do, and what can’t he? What’s normal, and what’s not? What should I expect of this baby’s abilities?

Some things are commonly known and have standard guidelines, but all too often, when it comes to sleep, there’s a dearth of knowledge, leaving many parents (and even medical practitioners) scratching their heads. That leaves many of us over-expecting and under-expecting in all the wrong places.

So what can your newborn do, and what can’t he?

To answer that, think back to what life was like for your newborn before he was born. It was dark, for one thing. Lots of rhythmic noises, nothing really unexpected and all sounds muffled by the surrounding amniotic fluid. Taste and smell didn’t vary much either. It was predictable and calm.

When that little baby enters the world, however, his or her senses are assaulted by noise, smells, lights, people—and the other stimuli of the world. It’s a lot to take in all at once, and babies especially can manage only bits and pieces.

How long? 45 minutes. Yup. That’s all. Your newborn can only tolerate about 45 minutes of activity before becoming overstimulated and overtired.

Surprised? You’re not alone. Most mothers I work with are shocked when they hear how long their little one can go before needing another nap. I know I was surprised, too. But some mothers thoughtfully nod their heads and say, “Oh, yeah, I did notice he starts to get kvetchy around 45 minutes.” And when my clients do get their children down to sleep before they get past that 45-minute mark, they’re often surprised to find that babies will go to sleep on their own.

That’s probably the No. 1 way moms tend to overestimate our newborns’ abilities. The second way? The “newborns can sleep anywhere” belief.

Belief, but not truth.

Since newborns can only handle a little bit of stimulation in little chunks and pieces, they’ve got a great strategy to use when it’s all just too much: habituation.

It’s a handy little tool that your newborn probably has to use too much. We’ve got a loud, messy world these days, and most of us just think our newborns can slip right into it. I mean, it doesn’t matter if it’s the middle of a party; your newborn will just sleep, right? Wrong!

When things get to be too much, a newborn will shut down to block it all out. He’ll look like he’s asleep, but that doesn’t mean he actually is.

What’s the problem with that? Well, once that extremely stimulating environment passes, and you get yourself and your baby into a dark, quiet place (likely when you’re ready to go to bed), THAT’s when your newborn is going to act up. Without the stimulation, showtime is over, and your newborn is back to himself. And he’s overtired, overstimulated and does not feel good. So he lets you know—by crying.

Keeping your newborn in a low-stimulus environment during both wake and sleep periods will enable her to eat well, sleep well and be calm while awake.

A recent client wasn’t sure what to do withShe could never seem to get her to eat her baby; it seemed there was never a good time to feed her. Either she was crying or sleeping, but she could never seem to get her to eat. We chatted a bit about what was going on, and she told me that the baby was in the living and dining rooms (read: cluttered, bright, noisy, lots of visitors) most of the time.

“How about when you’re in your bedroom?” I asked her.

“When we go into the bedroom, her eyes pop open! And I thought that was so strange because it’s darker in there.”

Bingo. Lower stimulation meant that her newborn was actually able to be calm and awake during her wake time. She slept better at the end of her wake limit and was then able to eat well, too.

So many parents of newborns struggle with what they think may be a colicky baby or reflux, or a whole host of other potential problems. Oftentimes, though, the most finicky babies are able to be calmed simply by their parents being aware of their limitations—and sticking to them.

(Disclaimer: The above article contains advice and tips that are solely the opinion of the author.)