If I lived 10K years ago I imagine I would have been frequently sleep deprived. Obtaining food, building shelters, and guarding against attacks were all higher priorities. We don't have any hard data on neolithic sleep patterns.
That's a good point, and one of my arguments for unscheduled sleep.
All the things you mention would indeed take priority, and we probably spent days sleep deprived at times, making up for it with extended long sleep when there was opportunity.
I think our lives were not nearly as difficult or demanding as some imagine, however, especially when you factor in the social and tribal factor. Sleeping in shifts would allow for plenty, attacks were not constant, especially with good shelter, and shelter only takes so long to construct, if that's necessary at all.
Remember, we started in an environment which provided everything we needed already, and one we were evolved for.
If you look at the lives of other apex predators like lions, bears, and eagles, their lives are pretty good in this respect, and their biggest threats are either their own species or humans.
