One of the yardsticks I've used over the years is how long I can talk on the phone. For several weeks now I start to crash after 10 to 15 minutes. This is really not long enough for me to have an enjoyable phone call. Before this I was able to talk 30 to 45 minutes. Occasionally even an hour. And it's not just the phone. If someone is here my limit is the same. But if there are frequent breaks in talking I do okay. Like when a caregiver is here. We usually talk for a few minutes at a time, and the rest of the time they are doing something else. Thinking for long periods of time does not affect me the same way. And I can sometimes watch TV for two hours. Or do something on the computer for an hour. So I think it has to do with conversation. When I crash I end up feeling sick for the rest of the day. Or sometimes just several hours. Not just fatigued, but a general crappy feeling throughout my body that is partially a worsening of the flu-like ache I have all the time, and partially a feeling I can't describe except to say it's a crappy body feeling like something is horrible wrong. I get the same feeling if i"m vertical too long.