Related personal story: I have severe obstructive sleep apena (OSA), and I went for several years before it was diagnosed.<p>During this time, it was not unusual for me to get very little sleep many days in a row. As a coping mechanism, I learned somewhat to &quot;half-sleep&quot;, where I would close one eye and relax that side while continuing to do things using the other eye.<p>I wouldn&#x27;t consider it sleeping just on one side of the brain, but there was definitely something different going on. I found that 2-4 hours of that would help my overall wakefulness.<p>Fortunately I had my condition addressed, but it would have been interesting to see if over time I would have developed into a full sleep-wake state of consciousness.