Yesterday I stumbled across “40 Facts About Sleep You Probably Didn’t Know (Or Were Too Tired to Think About)” from the National Sleep Research Project in Australia.

Here are some of my faves–and things I in fact did not know about sleep:

– Anything less than five minutes to fall asleep at night means you’re sleep deprived. The ideal is between 10 and 15 minutes, meaning you’re still tired enough to sleep deeply, but not so exhausted you feel sleepy by day.

– A new baby typically results in 400-750 hours lost sleep for parents in the first year

– REM dreams are characterised by bizarre plots, but non-REM dreams are repetitive and thought-like, with little imagery – obsessively returning to a suspicion you left your mobile phone somewhere, for example.

– Some scientists believe we dream to fix experiences in long-term memory, that is, we dream about things worth remembering. Others reckon we dream about things worth forgetting – to eliminate overlapping memories that would otherwise clog up our brains.

– Scientists have not been able to explain a 1998 study showing a bright light shone on the backs of human knees can reset the brain’s sleep-wake clock.

– The NRMA estimates fatigue is involved in one in 6 fatal road accidents.

– In insomnia following bereavement, sleeping pills can disrupt grieving.

– Tiny luminous rays from a digital alarm clock can be enough to disrupt the sleep cycle even if you do not fully wake. The light turns off a “neural switch” in the brain, causing levels of a key sleep chemical to decline within minutes.

– Some studies suggest women need up to an hour’s extra sleep a night compared to men, and not getting it may be one reason women are much more susceptible to depression than men.

– Exposure to noise at night can suppress immune function even if the sleeper doesn’t wake. Unfamiliar noise, and noise during the first and last two hours of sleep, has the greatest disruptive effect on the sleep cycle.

By Valerie Reiss. Amy’s on vacation.