At least, it used to be.
But we now live in a time when everyone we know, and a whole stack of people we don't know, are invited into our homes every day. It's called the internet and social media.
This intrusion into the safe space of our homes is affecting our kids, and it's time that us parents step up to help them manage it.
Technology in kids' bedrooms: a bad idea
What happens to devices at night-time is a big issue for families. Should your child be allowed to play games or chat to friends online, in bed, until they fall asleep? Or should there be a cut-off time, when devices are put down?
Well, you can't argue with science. One study found that kids who use devices at bedtime sleep less, get poorer quality sleep and are more tired during the day than kids who switch off earlier.
And it gets more interesting: further research says it isn't just using the devices that interrupts sleep. Even kids who have a phone or tablet device in their room - without using it at bedtime or during the night - still had that bad quality of sleep.
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So you can forget blue-light filtered glasses or switching off the wi-fi to save your kids' sleep. Simply having a device in their bedroom is keeping them awake.
What's good for the kids is good for the adults
I asked my nine-year-old about a "no technology in bedrooms" rule and she said, "Sure, but adults should follow that rule, too".
She's far from the only kid to see a double-standard. Last year, a US survey of 249 families asked the kids (aged between 10 and 17) their thoughts on household technology rules. Hypocrisy was one of the big issues they raised.
"While parents tended not to be concerned about different rules for parents and children, many kids saw that as hypocritical," the report says. "Children also found it easier to follow household technology rules when families had developed them collectively and when parents lived by them as well."
It's a widely considered best practice approach to parenting: model the behaviour you want your kids to follow. So, we too need to switch off during some parts of the day and all of the night, if we want our kids to develop healthy technology habits.
There are more issues at play
We are a generation of parents who grew up without having these factors at play; it's fair to say that we don't truly understand what it's like to be a teenager in this technology age.
A friend's pre-teen son told me recently that not responding to a message quickly is a social disaster. "If you don't reply within five minutes, your friend thinks you hate them and you're up for a big argument the next day."
Another friend's teenage daughter said, "If you put up a post and it doesn't get a certain number of likes within half an hour, then you have to take it down. Otherwise you're going to get teased at school the next day."
Our kids are sitting at home (which should be their safe places), worrying about whether their actions that night are going to have huge social repercussions the next day.
And we have no idea they have these pressures on them - unless, of course, we chat with them. You can't do that if they're locked away in their bedroom with their face in a screen until midnight.
The elephant in the room
The issue of technology in bedrooms goes even further - and this is one that many parents want to ignore. It's just too scary for words, but let's try.
"You need to keep electronic devices out of bedrooms for your child's safety," says digital parenting expert Ruth Dearing from Children and Technology. "Child exploitation and image abuse is now affecting one in five Australians; it's a massive problem and it's one that ruins lives."
"While your child can easily take a nude image of themselves in their bedroom behind a closed door, they aren't likely to take the same image in the middle of your lounge room!"
Kids in their rooms, with the whole big world of the internet at their fingertips, is bad news.
It's not a matter of trusting your child; it's a matter of being aware that bad judgment calls can easily be made, and that not every person in the internet is a good person - from online predators to school bullies.
I'm not suggesting that devices or social media are the devils in our children's once innocent lives.
But I'm aiming for my home to be a safe space for my children and I think you should too.
The story Have you checked the children? Why tech in the bedroom is bad news first appeared on The Sydney Morning Herald.