Not a little dark: really dark.

We always hear that it's important to sleep in the dark: "It's so your eyes can really rest", "it's so your brain knows it's night", "it's so your body can relax". Silence is also important, for similar reasons: "to quiet the brain". Hence the bedroom separated from the rest of the house, the electric lights with switches, the curtains on the windows.

But that's not why sleeping in the dark and in silence is so good. Anyone who has ever fallen asleep in the middle of a class, a meeting, an important lecture or even in front of the television knows that the brain is perfectly capable of withdrawing from the world: you don't have to turn off the world to fall asleep. In fact, it is precisely in the absence of external stimuli that we notice that the brain produces its own entertainment. Sometimes, it produces too much: my anxiously Aspie child's brain was a master at testing catastrophic thoughts - world wars, me forgetting to breathe if I didn't pay attention, my father not coming home from a trip if the plane crashed, all that "light" stuff - so I quickly discovered that the bedside clock radio, a technology from the late 1970s, took care of providing an external distraction. Then came MTV, playing music all night long. I would turn it down, close the bedroom door and fall asleep, until my mother came to turn it off in the middle of the night, advocating for the peace of my brain's external environment (nowadays she does the same thing: she discovered that she goes back to sleep after dawn if she puts on her mini headphones with CBN whispering in her ear).

Many years later I discovered the sleeping mask, sponge-like eye patches covered in a soft dark blue fabric that hugged my head and allowed me to open my eyes normally and not see anything, even sleeping on the air mattress right under the huge, beautiful windows in my cousins' living room. It was Sarahi, my hostess, who let me sleep after sunrise by offering me her own eye patches, which she then gave me as a present. Sarahi changed my life: I take this mask with me on every trip, which I call my eye bra (my eyebra!), with its shells perfectly fitted to the face - none of those pieces of cloth that airplanes once offered to all passengers, better than nothing but with huge holes on the sides of the nose, perfectly permeable to light. I still haven't found anywhere to buy another eye bra like it, and I'm already predicting the day when mine will crumble from so much use.

A few years later, I discovered additional soporific comfort in the heavy blankets with glass balls that became fashionable. By then, I had discovered that I was an Aspie, on the autistic spectrum, and the peace brought by the eight kilos distributed over my body took me back to memories of my childhood - and I finally understood why I insisted on sleeping with the air conditioning always on in my first room, even in winter: the device's constant soothing snoring came with the bonus of the weight of the many blankets needed to hold in the heat of my body in my private Siberia in the middle of Rio de Janeiro. I was lucky enough to have parents who didn't have to control the electricity bill at the end of the month, and to be the daughter of a totally Aspie mother (although to this day in denial!) who understood perfectly the importance of finding peace so that the brain could sleep.

This was my advanced level of night-time routine: by the age of 50, I had discovered the perfect pillows (one of the benefits of sleeping frequently in hotels: the compulsory exploration of new pillows), which accommodated and hugged my head just right; the perfect sheets, not satin, but satin cotton that caresses the skin; my heavy blanket, its eight kilos holding me still in bed like the comfort of a parent's arm cradling an adult; my faithful eye bra, still the same one given to me by Sarahi; and the snoring of my dogs at my feet throughout the night, a reminder that I wasn't alone in the world.

I was single again, and finally resolved to carry on like this, free spirit, with no one to claim my time for themselves since that person who would be worth my time apparently only existed in my head and "the great is the enemy of the good", yes, except when this "accept the good because no one is perfect" thing hadn't worked time and time again, so excuse me but leave me alone. Of course, then the world decided to laugh at me and dangle in front of my brain that man I didn't need to know, because we recognized each other right away as if we had always lived together, we just didn't know we were already together - and he was sleeping in a cave.

A cave, really: a windowless room (which therefore doesn't meet the requirements to be called a "room", I now know) tucked away in the basement of his house, underground. I think any normal, sensible woman would have run, not least because his living room with its stupidly soft and enveloping sofa was also in the basement (the "normal" living room was just for the record, he didn't use it), already in the dark. But when I went downstairs for the first time, I understood why he had made the basement his lair and I already felt cozy, safe, protected from the outside world, so I accepted the invitation to sleep in his room with no windows, no light, no outside sound other than our breathing.

I've never slept so well.

We also made our room on the ground floor of our house, partly against the earth. We're still hunting, black insulating tape in hand, for the lights that come in through the gaps in the blackout of the only window, the little green light that indicates that the phone charger is working (which, in the dark, is a huge light), the red light on the air humidifier. I've learned to put the phone in Do Not Disturb mode, where only calls from my parents and children pass through the sieve of the technology that detects who is calling me by the exact pattern of the air vibrations. The challenge now is to find a way to position the clock, projected on the ceiling, behind our heads, and with the minimum amount of light so that it is just visible without damaging our eyes.

The brain doesn't fall asleep because it has nothing to do. That isn't why sleeping in complete darkness, in complete silence, is so good - because without external stimuli, the brain turns itself around and produces its own entertainment, which is what dreams are: the day in review (but that's another story). Sleeping in absolute silence and darkness is wonderful because it gives you the same comfort as knowing that the house alarm system is on and, as in those comedies where the thief moves a string, any attempt to break in will be announced with sirens and banging pots and pans: with strictly nothing going on around you, the brain finally discovers itself totally safe in its most complete vulnerability.