What are pins and needles and why do we get them?

The fancy name for it is Parasthesia. It occurs when nerves don't get enough blood flow or when they are damaged. (Which is why you get it when your resting on your leg etc)

A bit about nerves

• Have an extremely high metabolic rate. Really, they consume energy a lot faster than most tissue in your body. (perhaps that's why pain makes you tired?)
• Impulses travel at around 25m/s!
• Neurons don't undergo mitosis, once they're gone, they're gone.

Anyway, as we know nerves have a high metabolism, if it doesn't get enough blood flow, it will shut itself down. The first to power down are the pain fibres, which is why you feel a sharp pinch. 

If you have pins and needles, one way to get rid of them is start shaking your arms/legs around like crazy, this will increase the blood flow back to your nerves and they'll be happy again!

Side topic, ever felt like bugs were crawling on you but nothing was there?

Known as formication, not to be confused with fornication which is about sex!

This can actually be the result of many different causes such as

• Wind blowing on your hairs
• Nerves being pinched
• Rubbing hairs on clothes
• Bugs crawling on your arm then magically disappearing

The most common is the first one, however formication is a known result from menopause, depression paranoia and many others, and in a rare case result in the person scratching themselves till the point they bleed.

However there is a very slight chance you have invisible bugs crawling on you, if you suspect this, don't go to the doctor as they'll think you're an idiot.