The short answer

Room sharing almost always goes better than parents fear. Get both kids' sleep solid first, keep the younger one in a cot, prep your older child honestly, set two or three simple rules, stay out of the room once they're down, and give it a few weeks to settle.

At some point, most families run into the same dilemma: you're out of rooms, or you want to turn a spare one into a playroom or study, and the solution is to put your kids together. It sounds simple enough until you actually picture it. One toddler is already a questionable sleeper. Add a second child into the mix, and it's easy to imagine the whole thing unravelling into a nightly party instead of a bedtime.

The good news is that room sharing almost always works out better than parents expect, as long as you go in with a plan and give it time.

Get everyone's sleep as solid as you can first

Before you move anyone in together, spend a few weeks getting both kids' sleep as consistent as possible. A rock solid bedtime routine and reasonably settled nights beforehand gives you a much better foundation to build on. Trying to fix two separate sleep issues at the same time as merging rooms makes it much harder to tell what's actually causing what.

If the move is tied to a new baby arriving, try to avoid combining rooms in the three months immediately before or after the baby comes if you can help it. Big siblings often go through a rocky sleep patch in those early months regardless, so adding a room change on top of that is asking for a harder ride than necessary. Sometimes it's simply not avoidable, and that's fine too. Kids adapt. It just tends to take a little longer.

Keep your younger child in a cot for as long as possible

If one child is still in a cot, keep them there through the transition rather than moving them to a bed at the same time. There's no real cutoff for how long a child can stay in a cot, some stay in one well into their fours, so there's no rush to move them out just because a sibling is moving in. A cot gives a clear physical boundary that makes the adjustment to room sharing much easier, since a child who is contained is far less likely to end up wandering, or ending up in bed with their sibling at 2am. Plus, it can be helpful for them to still have their familiar sleep environment with them in the new room.

Prep your older child simply and honestly

You don't need to build up a big exciting story about how wonderful it's going to be. A day or two before the move, tell your older child plainly that their sibling is going to start sleeping in their room. If they push back or say they don't want it, resist the urge to talk them out of the feeling. Just acknowledge it: "I know, it's a bit different to share your room with your sister." Trying to convince them it'll be fun tends to backfire, whereas acknowledging the feeling helps it pass more quickly. Reassure them that they will still have their own bed, and their own toys. Sharing a room can lead to increased possessiveness, which is totally normal.

Set a few simple, repeated rules

Give your older child two or three clear expectations for the new setup, and repeat them together each night while everyone gets used to it. Something like:

• Everyone stays in their own bed or cot.
• If you hear your sibling crying or making noise, stay quiet and go back to sleep. A parent will come if needed.

Keep it short. The goal isn't a long list of rules, it's a small, predictable script your child can hold onto during a change that might otherwise feel unsettling.

You don't need to sync their bedtimes

If your children go down at different times, there's no need to force them onto the same schedule right away. Keep your younger child's earlier bedtime if that's what's working, and bring your older child in when it's their turn. Over time, most families find the gap either closes naturally or simply stops being a problem, since kids get surprisingly good at sleeping through a sibling's routine once it becomes familiar.

Be a confident leader

Sometimes there can be issues when siblings start sharing a room about how bedtime will look. One child wants to listen to an audiobook to fall asleep, the other wants relaxing music. One wants the night light on, the other wants it off. Don't give them too much power over these things, as they'll fight about it for the sake of it, not because they actually care that much about the thing itself. Consider your children's individual needs and make a decision based on this. Tell them the plan ahead of time so the battle doesn't start at lights out, and empathise with whichever child is having to compromise.

For example, we used to read books together on my eldest daughter's bed before they got a bunk bed (her younger sister was in a cot still). When we got the bunk bed, I automatically sat on the bottom bunk to read books, but my eldest was very upset that we were reading on her sister's bed, not hers. So now we sit on the floor on pillows to read books: a neutral space. I wasn't prepared to negotiate whose bed we were reading on each night.

Expect a bumpy adjustment period, then let it settle

For the first few days or weeks, bedtime will probably take longer. Siblings tend to chat, laugh, or try to keep each other awake once they realise they have company. As tempting as it is to referee this from the doorway, it's usually best to stay out of the room once they're down and let them work it out themselves. Left alone, most kids settle far faster than parents expect, and the entertainment of a shared room wears off much sooner than you'd think. Trust them to learn their boundaries for stopping with the giggles and chatting, so long as they're staying in bed.

If wake times don't match, plan for it rather than fight it

One common snag is an early riser sharing with a later sleeper. If one child wakes and quietly entertains themselves, reading, listening to an audio player, playing in bed, they're less likely to disturb a sibling than one who calls out the moment they're awake. If your early riser is used to calling out for you, it may be worth shifting that habit slightly beforehand, so they have a quiet, independent way to occupy themselves without waking the room.

Or you can use an "ok to wake" clock so they know when it's ok to call for you or come out of their room. It's still likely your younger or later sleeping child will get woken earlier at first, at least while everyone adjusts, so go in expecting a short stretch of early mornings rather than a permanent one.

The bottom line

Room sharing sounds like a recipe for sleep chaos, but in practice, most kids adapt far faster than their parents do. Go in with a solid routine, a cot for as long as it makes sense, a couple of simple rules repeated consistently, and the patience to stay out of the room once they're down.

Give it a few weeks before judging whether it's working. Most families find that what felt like a daunting change becomes just another normal part of the routine, and often, a lovely way for siblings to build closeness that a shared room uniquely creates.

For more sleep help, browse my sleep guides and sibling guides, or book a 1:1 consult.