I recall one day when I decided to call one of my friends. She soon came onto the line, sounding tired. She explained that she had just got back from a long trip and was worn out.
Nevertheless, we ended up talking for a while anyway. The conversation was rather interesting, as she would frequently say something, and later forget she had ever mentioned it. She had invited me to come over to her house later at least fifty or sixty times during the time we were on the phone, and when I pointed out that she had already done so, she had no recollection of it.
At one point, she grew quiet for a long while, and I started saying her name and trying to get her attention. The silence lapsed for a few minutes, until finally she returned. She apologized for falling asleep, and I suggested that perhaps she should get some sleep and call me back later.
When we did talk later, she was more rested and her memory was better. She still didn't remember much of what she had said to me in our prior conversation, though, and invited me to her house again.