Sleep
Gaara had read once, somewhere, that the first day without sleep, corneas erode subtly, and your white blood count might decrease.
On the second day, headaches are common, as is increased apetite, and a tingling lightheadedness some even find attractive.
On the third day, there is markedly decreased mental activity. Vision blurs. Some other symptoms are dizziness, confusion, and memory loss.
After that, hallucination sets in.
Gaara had also read that in some barbaric far-flung places, sleep deprivation was used as a form of torture.
At nights, while his bitter world succumbed to their shared nonexistence, the blissful mental death that excluded only him, he would will himself out into the desert that lurked at the edges of the Sand. He would lie on his back on a dune, and imagine that he was 100 feet under, in the deep dark coolness beneath the shifting sands, sweetly entombed. It would be a kind of sleep, his globed eyes unseeing, at last, his fingers spread like a pale enduring blossom, each surrounded, imprisoned. Down there in the silence there would be no air, only sand pressed to his child's lips, and eternal rest, an end to the irritation and agony of hot desert winds. He would imagine this, as he lay on the dune, but the stars overhead forbade him from the gentle sleep. He imagined that they, pearl-strewn and sterile-white, were the scattered ashes of his mother, who had rebirthed herself in him. They were all her eyes, and were as he knew her to be; pale, cold, and far away. She told him he must not sleep. And the devil inside him enforced it.
Most days it was hard to think. Gaara had become used to how the fearful voices around him were the scratchy whispers of wasps, crawling eye-aching yellow and black behind his ears. He was used to how the world would dip, orbit in and out of control; his eyes were nothing but green, a color not found in the Sand and that he had never seen before. He had no pupils, and his eyes were ringed with black.
The hallucinations he was used to too. It wasn't uncommon for men to melt like candlewax before him, for the sun to dilate like an eye, for the ground to breathe. It wasn't uncommon for his mother, beautiful as a photograph and fresh-flaming from her funeral pyre, to whisper words of hatred in his ear.
He was a child. He watched the cycles of day and night, summer and winter, birth and death, slip past without him; exempt, alone. Can you feel alone if you've never been any other way? He had found his role in life- he would be death. He let them think they had control over him, a leashed dog- go kill! Stop! Now kill again! It was nice, in a way, to pretend that at least someone had control over his raging life, and used it with a purpose. But there were faceless victims buried in the sand they would never know of, children who had not wanted to play with him, an old man who spat in his path, the young mother who had screamed that he was a monster. There would be their faces, first, full of hatred and fear, sickening, and then the cosmic crunch, the physical pain that could never amount to what he bore inside. An explosion of human, though the blood never touched him. The devil in his chest made sure of that.
Gaara embodied his Father's deepest abhorrence- lack of order. One day Gaara had asked him as he stood in his study, arms crossed, if mankind was made for order, for reason, why are there wars? It is only reasonable to create, raise a child, build a temple, organize an empire, and yet why the dark desire to smash sandcastles? The entirely human urge to kill? That was what he embodied, the dark side of nature. His Father had his share of darkness, but he dressed it up in white and paraded like a saint before his people. There was murder to save the world, just one, then just one more, then a million; wars for peace. It was a twisted world and Gaara was a twisted child. He had started innocent, and he still was, in a way, a tool, unknowing, most of his days hazed and reddened without sleep, though there were those lucid days in between. Sharp as cut glass in winter, they were, and he saw the cosmos in a panorama of smoke and carnage, teeming ants springing up every time they were mowed to the ground. They writhed in their billions beneath the stretched- canvas sky. It looked smooth to ordinary eyes but Gaara knew that if it ripped you would see galaxies of frenzied churning gears, levers, the clockwork that kept man killing man killing man, ticking like a waiting bomb of iron laced with flesh.
His mother would be happy.