Sometimes when I can’t sleep at night, I lie in bed and try to remember the exact layout of houses that I’ve lived in. I’ll imagine myself walking around them, picking out as many small details as I can.

There are four that I can remember with real clarity; the house on Harris where I spent all of my early childhood, my Grandpa’s house in Staffordshire, where I used to spend lots of holidays, the farmhouse in the Borders where I spent most of my teenage years, and the house in Edinburgh that I lived in until a year ago.

There are other places that I can remember a few details of. There was a white cottage on Lewis where I lived with my Mum for a year, and then a townhouse in the Borders where I also spent about year. And of course, there were several flats in Edinburgh where I lived as a student. But the memories of those places are a bit fuzzier.

In the Lewis house, I can remember crawling under my bed and hiding sweets between the wooden slats of my bed. I can remember accidentally starting a small fire in the garden with a bottle of meths and having to stamp it out with my wellies. I can remember watching my stepbrother doing backflips all the way across our garden.

In the Borders I remember that my bedroom was dark blue, and it’s where we lived when I had chicken pox. I remember that I had a My Little Pony that smelled of cherries, and we had a collection of frog ornaments that were lined up along the stairs. I remember very clearly hearing the word homosexual on the radio one morning and asking my Mum what it meant. I have absolutely no recollection what her answer was.

In my first student flat I slept in a high cabin bed, and covered my walls with pictures that I’d cut from The Face and Sky magazine. In my second one the boiler cupboard was right at the head of my bed and it woke me early every morning when my harder working flatmates got up to shower. And in the third one I had a resident mouse in my bedroom.

So I can remember wee bits and pieces, but the layouts and the minute details of every room are not imprinted on my brain with any permanence. I don’t remember the postcodes (or even the street names), and I’ve forgotten the wallpapers and the colours of the front door.

The four houses that I can remember clearly are not just the ones that I’ve spent most time in. They are the ones where the most memories have been created.

My Grandpa died when I was twelve, so I haven’t even been near his old house for more than fifteen years, but I could still draw you a pretty accurate floor plan. I could tell you which cupboard used to house those blue glass Milk of Magnesia bottles, and which shelf of the bookcase his Scots Magazines lived on. I could find all the light switches in the dark, tell you how many steps there are in the pantry, and show you which pane of glass he cracked with a cricket ball as a young boy. (My Grandpa is the only person I know who spent his entire life living in the same house.)

Similarly, it has been more than ten years since I’ve been in our Borders farmhouse. But now, as I lie awake in bed and imagine myself walking round, I can remember it all; which creaky floorboards to avoid when you creep for a wee in the middle of the night, which railing of the banister is a bit shoogly, which drawer the crisps for my breaktime snack at school were kept in.

I have no wish to go back and visit any of those houses. They would undoubtedly be different, and I’m not sure how that would make me feel; perhaps a bit like being in one of those uncomfortable, disorientating dreams where things are familiar and yet not.

The one house that I do go back and visit is my childhood home on Harris, because my Dad still lives there, and the thing that strikes me every time is how the scale has changed. The house and garden that seemed huge to me as a child now seem quite dinky. I remember living beside a huge, foaming churning river… but it’s actually quite a gentle wee stream. My head is now level with the ‘high’ branches where my brother’s tree house used to be. The cupboard under the stairs is just that – a cupboard – and not a big, dark, spooky abyss. The staircase only requires small steps, not giant strides.

It is a good lesson in not romanticising my past, and not to become too attached or misty eyed about something which is really just a memory. Houses are a place to live, and then to move on from, taking the best associated feelings with you, but leaving the bricks and mortar behind.

I’ve just finished reading I Saw Ramallah by Mourid Barghouti, and there is a line in that which has stuck with me, because it sums it up so well.

“My relationship with place is in truth a relationship with time.”

I would do well, next time I can’t sleep, to remember that.