[tunap]

My initial thought follows this line. Even if a subject doesn't experience actual sleep deprivation, the constant external stimuli are still omni-present, regardless of how well the conscious mind tunes them out. Perhaps sub+consciously parts of the brain never get any rest, even while sleeping?

I know I feel less refreshed if I fall asleep and media or traffic outside is constant. A hotel room facing a freeway often leaves me waking unrefreshed, which can be partially mitigated if the room's fan blower is left on for continuous, monotonous white noise masking.

[unclebucknasty]

Yeah, it can disturb your all-important REM sleep without causing you to fully awaken, so you're not aware that your sleep has been disturbed. You're just not as refreshed by morning.

Interesting about the fan blower. My wife started using that to prevent our young kids from being awakened by normal household noise. It reminded me of something I'd read years ago about people who worked in server rooms losing hearing sensitivity in the range of the constant low-level hum. Not sure how much exposure was required, but I encouraged her to use it sparingly.

[dpark]

I wonder if that's permanent hearing loss or temporary desensitization. It's not hard to imagine that the brain eventually starts to tune out a constant 60db server hum without any mechanical or permanent hearing loss.

[tunap]

Get them a little fish tank! The humming pumps and trickling water for most of my adolescence didn't make me too demented. Probably.