I bought my mum a grounding sheet. Now she is sleeping like she is 50 again.

My mum is 71. She is sharp, opinionated, and slightly suspicious of her own daughter — which is to say, she is the woman who raised me, and the relationship has not fundamentally changed since I was 15. She lives two streets away from us in Sydney. She does her own shopping. She still drives. She has lunch with the same six friends every Wednesday at the same Italian restaurant where she has been having lunch since 1996.

She also, for the last nine years, has not slept through the night.

The gift problem.

If you have parents in their late sixties or seventies, you know the gifting problem. They have everything they need. They do not want a vase. They have stopped wearing jewellery they have to wash up to. They will not accept money. They politely refuse experiences because they say they are tired. Birthdays and Christmases become a slow-motion negotiation between you and your siblings about whether anyone has had an idea, and the answer is always no.

I had run out of ideas. For her seventieth, my brother and I had gone in together on a weekend at a wellness farm. She had loved the food, hated the breathwork, told the masseuse her shoulders were "perfectly fine, thank you," and come home tired. We had nothing left in the bag.

So when her seventy-first birthday came around in March, I did what I always do when I have run out of ideas. I looked at what was wrong, instead of what was missing.

What was wrong.

What was wrong was the sleep. Every time I had lunch with her, every time we drove anywhere, every time she came over to ours for dinner — she would, at some point, say, "I was awake at 4:10 this morning." Sometimes 3am. Sometimes 5. But always before her body wanted to be. She would shrug it off. She would say, "It is just what happens at this age, darling." She would change the subject. And then thirty minutes later she would yawn.

I had heard her say this for nine years. I had heard her four friends — also in their late sixties and seventies — say variations of it for the same nine years. The accepted narrative inside that generation is that sleep gets bad and stays bad and you do not complain about it.

What I had been hearing about.

A friend of mine — her mother is the same age as mine, similar setup, similar early-wake-up pattern — had bought her mother a grounding sheet about eight months earlier. She mentioned it in passing at a barbecue. She said, "Hannah, my mum is sleeping past 6am for the first time in years. It was a sheet."

I had filed it. I did not think about it again until I needed a gift.

What I sent her.

I bought her the Premium Grounding sheet — the slate-grey, stainless-steel-woven one that goes under the fitted sheet — and I wrote her a card explaining what it was, how to set it up, and that she did not have to like it and that there was a 90-night return window. I did not tell her how much it cost. I did not tell her my friend's mother used one. I just wrote, in the card: "Try this for thirty nights. If you do not like it, post it back and I will buy you something else. If you do like it, do not tell me until day 30 — I want to know whether it is real or whether it is the placebo of being thought about."

The package arrived on her seventy-first birthday. She rang me. She thanked me for the "very strange present." She said she would try it. She said, dryly, "I assume this is a phase you are going through."

What I heard back.

On day 4, she sent me a text — and my mother does not text, she calls — that said only: "Hannah. I slept until 6:15."

On day 9, she rang to tell me she had slept seven hours and forty-five minutes the night before and that she was reading the Saturday paper "in a chair, like a normal person, not in bed, propped up, like someone in a Victorian novel."

On day 21, she rang to say that her friend Margaret — same age, same sleep, same lunch group — was now considering ordering one. Two weeks later, Margaret had one. Three weeks after that, two of the other lunch ladies had ordered them. As of the time I am writing this, four of the six women at the Wednesday lunch table are sleeping on a Premium Grounding sheet, and three of them found out about it from each other, not from their daughters.

What I learned about gifting parents.

Two things.

One — they do not want more stuff. They want something they have not been able to get on their own, that you noticed they had stopped trying to fix. My mother had stopped trying to fix her sleep four years ago. She had accepted that 4am was just what her body did. I noticed. She did not say "thank you for the gift." She said "thank you for noticing."

Two — once they find something that works, they tell their friends. There is no marketing channel more efficient than four 71-year-old women at lunch on a Wednesday. The Premium Grounding people do not know how many sheets they have sold off the back of my mother's Wednesday lunch table. But I do, because I count when I am there.

What I would tell anyone with a parent over 65.

It is the cheapest meaningful gift you can buy. It costs less than the wellness-farm weekend my brother and I split last year. It comes with a 90-night money-back trial, which means there is no risk — if your parent does not like it, you send it back and they refund you. It comes with a 10-year warranty if you order today, because Premium Grounding offer that on the first 60 orders each day.

It is the gift my mother will tell her grandchildren about. She still has the card I wrote her, on the kitchen sideboard, propped against the salt shaker. I noticed it the last time I went over for lunch.

She has not said anything about it. She just left it where I would see it.

"It was the strangest birthday present I have ever been given. It is also, by some distance, the best one."