From
Mind Hacks:
Dr Allison Harvey (now of UC Berkley) took insomniacs and measured how much they actually slept during the night. Despite the insomniacs reporting that they had only slept for two or three hours, they had in fact been asleep for an average of 7 hours - only 35 minutes less than a control group who didn't have any problems sleeping.
This shows that insomniacs (and probably the rest of us) are very bad at judging the time it takes us to get to sleep, and the time we actually are asleep. It also suggests that worrying about sleep, and our beliefs about how we've slept, have a big role in the negative affects of what (we believe) is a sleepless night.
Which just goes to show you, all my muckity-muck a few posts down about dreaming the life, living the dream - it is much more often
exactly what you make of it then most people would seem to believe.
I believe I slept well last night. Did you?