I have two such perceptions which may or may not be related.

Since I am very young every now and then I have had an temporary alternation of vision. Suddenly everything looks much farther away than it is and as if I'm looking through a tunnel with dark and/or blurry sides. When I was young, maybe 12 years old and told my parents this the thought I were tired. But I wasn't. It happens during the day. It is distracting but it goes away after closing the eyes for some time and resting. Or whatever. Doesn't stay longer than an hour.

The other thing is a hightend perception of touch (and possibly other senses) which starts during drowsiness before sleep sets in. I can feel every ripple on the bed towel. I feel every unevenness on the bed post. I am aware or every smallest crumble in the bed. It is interesting and of course I get more awake but then it goes away after some time.

The last time it happend I tried to determine whether the perceptions is really more precise or whether I just feel it as more intense (like contrast enhancing a picture doesn't show more details). It was inconclusive (as I didn't have suitable material to test and when I get up the effect faded). I still think that at least I was aware of more details but could have felt them with proper training even without this state.

When I say every now and then I mean a few times a year and the last time was longer than a year ago. It declined with age.

I understand that comparable effects are not unusual for migraine which I also have sometimes, but these do not seem to correlate for me. I once looked up the effect but can no longer find the link. Sorry.

I knew that these effects where somewhat special but I didn't assume that everybody has them nor that nobody else has them.