Why does my hands arms and legs fall asleep when sitting too long an i'm always cold?

Couple of Things: It is unlikely at your age that you would have neurological or vascular issues causing your symptoms. My first thought would be to check a thyroid stimulating hormone (TSH) level, alongside an anemia panel and suggest that you ensure adequate hydration in the meantime. A primary care physician can obtain the above tests and discuss the results and further thoughts with you.