Ten Facts About Sleep

With the end of Daylight Savings Time about ten days ago, I've been trying to re-adjust my body's internal clock.  It seems to take me at least a week to adapt my sleeping when I travel across time zones or endure the switch to or from Daylight Savings Time.

I recently read and reviewed a book about sleep, and it was full of interesting information about the science and culture of sleep.  Here are ten facts, all from sleep research, in no particular order:

• People can partially awaken from REM (rapid eye movement, the deep) sleep, but they cannot move.  REM muscle paralysis is carried over into wakefulness.  This sleep paralysis goes away by itself after a few minutes, but can be frightening (page 11).
• A person’s core body temperature drops to facilitate the onset of sleep.  Body temperature is lowered by increasing blood circulation in the surface of our bodies.  Since hands and feet have a large surface area, warm hands and feet are an unmistakable sign that the body is getting ready for sleep (pages 13-14).
• Melatonin, a hormone released by the pineal gland that promotes sleep, is secreted starting in the late afternoon and early evening and reaches its peak while we are asleep.  If we open our eyes and receive strong light impulses through the optic nerve, the pineal gland immediately stops producing melatonin, which causes us to awaken (page 14).
• "Nap shops," where exhausted workers can rent a short-term sleeping space, are very popular in Japan (page 49).
• Are you an early bird or a night owl?  The next time you have the next day off (ideally, during a vacation or a break from school), write down what time you go to bed and when you get up the next day.  Then determine your sleep midpoint by dividing the length of time you sleep in half.  Early birds have sleep midpoints before 3 AM; night owls have sleep midpoints after 4 AM (page 63).
• Insomnia is more likely to affect women than men (page 82).
• Snoring is more frequent in men (page 83).
• The ideal room temperature for sleep is between 59 and 77 degrees Fahrenheit (page 92).
• Women who smell peppermint before going to bed sleep longer, with more SMS (slow wave sleep) and less REM sleep.  Men did not experience the same effects, but said they felt more awake and refreshed in the morning.  However, if the scent of peppermint is present all night long, it tends to awaken people from light (stage N1 and N2) sleep, making it difficult to fall asleep quickly (page 113).
• Lavender, jasmine, and vanilla are soothing scents that can help you fall asleep and stay asleep, but can have undesirable side effects in the morning, such as with tasks involving physical exercise. (pages 112-113).

More facts about sleep: 16 Things You Didn't Know About Sleep (infographic)
and 60 Eye-Opening Facts About Sleep.