I did do reaserch and i may be wrong about the xanax but I have already verified : suffocation is painful, and dropping yourself while hung will break the cervical vertebrae and instantly make you loose conciousness
You don't, necessarily. When the spinal cord is severed at a high point it may traumatize the brain stem, which can result in near-instant loss of consciousness and cessation of breathing.
A little lower and the brain stem may be undamaged but nerves which play a role in the autonomic nervous system may be damaged - these nerves help regulate many bodily functions including breathing, heartrate, and blood pressure.
The result may be apnea, a cessation of breathing, or "spinal shock," a drop in heartrate, blood pressure, loss of bowel and bladder control, sweating and loss of motor function, which untreated can be fatal.
But the neck can also be broken low enough or in a manner in which autonomic functions are retained, with the severity ranging from pain (and great risk of subsequent damage to spinal nerves from positional trauma and bone shards or swelling and compression) to varying degrees of paralysis of voluntary motor function as well as voluntary control over breathing etc.
A patient may have a broken neck or back and be upright and walking around only to lose their life or control of their limbs later. They do not necessarily even feel pain, as adrenaline may mask pain or relevant nerves may not be functioning properly.
This is one reason victims of trauma such as traffic accidents or falls are routinely placed in spinal immobilization until x-rays can confirm they are not in danger.