Why can my body function without sleep?

After 72 hours without sleep, most people experience an overwhelming urge to sleep. Many are unable to stay awake on their own. Going three days without sleep profoundly limits the ability to think, especially executive functions such as multitasking, remembering details, and paying attention.

why?

because it has set its self in survival mode.

7 days? idk but heres the effects

If you continue to operate without enough sleep, you may see more long-term and serious health problems. Some of the most serious potential problems associated with chronic sleep deprivation are high blood pressure, diabetes, heart attack, heart failure or stroke

Without sleep, it causes more stress, your body will not properly work, and because you can sometimes feel overwhelmed. You can also feel weak and might even lose your focus during school hours. I, sometimes, do not sleep until maybe 1 or 2 am, and when waking up, I feel dizzy and lazy. I stress a lot when I stay awake after midnight. So, I suggest, that sleep is good for you :)