Very odd dog behavior?

We have two multi-poos - one male that is about 4 years old and a female that is almost 3. Both appear to be in good health and are active. Several months ago, our male would pace and stand in one place for hours staring at nothing of significance. We took him to bed with us, and he would literally stand on top of me staring at one place - needlessness, he didn't sleep and neither did I :( This behavior lasted through the night and the next morning and since then he as been fine - no further episodes. Fast forward two months and now the female is exhibiting the very same behavior - standing in one position, not moving and staring into one place. I'll take the dogs outside where they are active and when I bring them back into the house, she assumes the same position staring at the point. This started about two hours ago. I have read about cognitive disorders, but to have two dogs exhibit the same behavior at different times and then the behavior goes away and at least for the male has not returned. Thanks for your read and reply.