I've noticed some variation in my need for alone time. When I'm at home in my comfort zone, my tolerance for external factors is much lower. If someone is around for too long, I get unresponsive. My closest friends have learned that this is a sign that they need to give me space. The more familiar I am with you, the longer I can be around you, but even my best friend can't stay over more than a night or two. Outside of my own home, I can go for somewhat longer stretches. My brain kind of goes into autopilot mode, and I tend to blend more socially. Of course, the necessary recovery time afterward is considerably longer.