I'm so desperate to get my baby to sleep I bought him a car.

There’s no set time when you have to replace your child’s cot with a bed, says paediatric sleep disorders expert Deborah Lin-Dyken.

She says it’s usually between the ages of one-and-a-half and three-and-a-half.

“It’s often best to wait until your child is closer to three, since many little ones just aren’t ready to make the transition. Of course, you’ll need to move your toddler to a bed when he’s simply too big or too active to sleep in a crib anymore,” she writes on US website babycenter.

My son, Charlie, is almost two and he has started to karate side kick over the front of his cot. I started to worry it would tip.

He’s never been a good sleeper so I thought perhaps a change in circumstances might ignite a newfound love of his own sleeping quarters.

Maybe he would even sleep through the night.

So I did yet another thing I never thought I’d do as a parent. I purchased a car bed. A big red ugly car bed.

Charlie and his new giant toy. Image supplied. 

My son is crazy about cars. He says: "Red car," on repeat. Sometimes it's: "blue car," or "gold car," or "yellow car".

Every day, every hour, a car will get a mention.

So now he has an ugly big red car in his room. It's my newest, most desperate plan to get some sleep.

The bed base is a pre-loved $60 Gumtree find but we bought a new mattress.

It was a hit, at first. He jumped. He squealed. He said "car bed" on repeat. He even went to sleep in it with only 15 minutes of coaxing. Then came the post midnight drama.

I heard my door slam shut. There was my son standing very still (which never happens) with his eyes closed. I picked him up and he didn't make a sound. He went straight back to bed but as I went to leave the room he woke up and screamed.

Then, this morning after 4am I turned to find him locking eyes with me less than a ruler-length away from my face.

"Mummy," he said once I had my eyes had pulled focus.

It's hard to believe the cot used to be too big for my son. Here is is when he was teeny tiny. Post continues after video.

The car bed didn't change our life.  We tried all the tricks, we went shopping for the new bed as a family, we created some excitement around it - but it hasn't worked.  His evening routine has grown to 45 minutes of trying to get him into the big clunky thing and stay there.

"Some toddlers simply aren't ready for a bed. It takes a certain amount of cognitive development for your child to understand that a bed has imaginary boundaries that he must stay within," sleep expert Deborah Lin-Dyken told Babycenter.

"If your great sleeper all of a sudden takes a long time to fall asleep at night, gets out of bed many times, or wanders around the house, he's probably not ready for his own bed."

We have always had post-midnight dramas but they are even more unpredictable now he can climb out and walk or sleep-walk around.

I'm just glad I haven't sold the cot.