I tried polyphasic sleep where you sleep 10 minutes every 3 hours, except I couldn't fall asleep quickly enough so I didn't sleep at all for >72 hours. The strange thing is that I got the idea that I was somehow more awake, more focused. All the background thoughts in your brain disappear, and it makes you think you have laser focus on what you are doing. Except that you objectively suck at what you are doing...
A few weeks after that experiment I found out that some of my memories were missing. I was in high school at the time and I took a university course in classical mechanics with a few friends. This meant going with the train to a different city several times per week, but I had totally forgotten that I did that. I only realized this when my fiends kept talking about it as if I was there too. The memories did come back later; the lack of sleep only only broke the reference to that memory and when the reference was restored the memory itself was still in tact.
A few weeks after that experiment I found out that some of my memories were missing. I was in high school at the time and I took a university course in classical mechanics with a few friends. This meant going with the train to a different city several times per week, but I had totally forgotten that I did that. I only realized this when my fiends kept talking about it as if I was there too. The memories did come back later; the lack of sleep only only broke the reference to that memory and when the reference was restored the memory itself was still in tact.