This is something that isn't easily verbalised, yet it is very real. It is something I couldn't possibly fathom until I had children myself.
I went from having to think just for myself, to having to think for 4 more little human beings.
That's 5 people to dress (and by dress I mean pick and purchase clothing for, wash clothing for, have clothing layed out for).
5 people to feed (and by feed, I mean picking and purchasing groceries, plan meals, and cook and serve said meals, for 5 people).
5 people to wash (and by that I mean shower or bathe 4 small humans in the evening -which is no mean feat, then sniff myself wondering whether I'd get away with holding off showering until morning).
I have struggled with the mental load in the past, when I was new to it. It made me feel overwhelmed and exhausted at times.
But since I was diagnosed with Type 1 Diabetes a year and a half ago (an autoimmune disease in which the insulin producing beta cells of the pancreas are destroyed) my mental load has increased 100%.
On top of the usual thoughts, worries and notes to self, I have to be aware of my blood glucose levels at all times. I have to test, and treat, and inject myself.
The mental load means having my brain in overdrive from the minute I wake up early in the morning until I close my eyes late at night.
There are bottles to be made. Breakfasts to be served. Nappies to be changed. Uniforms to be put on, and missing shoes to be located. There are lunches to be made, and bags to be checked, and dishes to be done.
There are reminders to be given. "Try to finish your banana!", Don't forget to brush your teeth! ", "Turn off the light in the bedroom please!"...
Whilst running around with my 1 year old on my hip, I try to pick up toys and clothes. Make a mental note to put on a wash of whites. Make a mental note to swing by the shop and pick up fresh milk. Make a mental note of making an appointment with the GP. Make a mental note of all the things that need doing around the house today, and wonder how far down the list I'll get.
Then smirk to myself - I know I'll be lucky if I get a start on the list at all.
After the school run, there will be more nappies to be changed, bottles to be made, games to be played. There will be hoovering, and cups of cold tea, and rocking my baby to sleep.
Once I've collected my older children from school, there will be homework to be done, clothes to be changed, dinner to be served, dishes to be done. There will be chats about their day, and refereeing squabbles, and showers to be had. There will be bedtime stories and cuddles and extra trips to the bathroom. And then the house will be quiet, once everyone is asleep.
But the mental load doesn't sleep, not until I do.
There's people to text, phonecalls to be made, an article to finish, a meeting to set up for work, the novel I'm trying to write.
Dirty dishes have reappeared in the sink, and the pile of dirty laundry seems to be higher than ever, despite the three machines I managed to squeeze in today!
My partner works long hours of heavy labour, 6 days a week. He helps out when he can, on his one day off, or in the evenings when he's home.
But he is blissfully unaware that there is such a thing as a mental load for me, as he has never had to hold the fort by himself for an extended period of time.
Yes, it is exhausting.
But it is also so rewarding, for my little people are thriving, and I am so lucky and thankful that they are healthy and happy.
And I know that, in years to come, I will miss being this busy. I will miss being this needed.
And I will look back on this time in my life with nostalgia and great fondness.