If we lived in a barn for the animals, with a hayloft over, where we all slept, and husband was out gathering while I made flour by hand under a rock and weaved our own thread during the day while the NUMEROUS offspring were in charge of looking after chickens, eggs, dogs, planting hoeing, fetching water, learning all the skills necessary not to die over the winter including food preservation, then yes, we’d all sleep together. Instead, we’ve chosen to artificially limit the number of children we have and pretty much on that list is outsourced. As a result, I’m going live much longer than 38.
In reality, rooms are small now, we don’t sleep on the floor on a mound of bedding with room for everyone, ‘bedtime’ and ‘sleeping at night’ have both become centred in the society in which we live, none of which really suits that style of sleep.
Our children are being habituated into our society from the second they are born, with very little of it ‘natural’ any more. Sleep is no different. We spend our lives teaching them to live in the world they find themselves. As a species, the reason we thrive and are all over this planet is that we adapt extremely well (in most cases) to the surroundings we in which we find ourselves (or build for ourselves).