Dec. 9, 2011 -- Tired? Tired of commuting? Tired of being tired on your commute? Despite the chaos among the throngs of fellow commuters, nodding off during a morning commute could do some good before starting your workday ... but not that much.
The New York Times published a story Thursday discussing an experiment carried out by Dr. Carl Bazil, director of the epilepsy and sleep division at Columbia University Medical Center.
Curious as to whether a few moments of shuteye on a chaotic subway helps the body refresh, Bazil recruited Dr. Brandon Foreman, a 30-year-old neurology fellow, to test whether the new dad's naps on the subway offered any restoration.
Foreman reported that he could fall asleep anywhere. That turned out to be true when he fell asleep on the busy New York City A train.
Once asleep, Bazil's team attached wires and a monitor to Foreman's head to measure his brain waves. The team found that, during the 23.5 minute ride, Foreman slept for 10 minutes. For three and a half minutes of sleep, Foreman reached stage 2.
Stage 1 sleep is often defined as a drowsy sleep, in which some people twitch and jerk at the onset of sleep. While experts do not consider it a restorative sleep, some restoration can be felt when the second level is reached. During stage 2, the body temperature begins to drop, the heart rate slows and the brain produces bursts of rhythmic brain activity known as sleep spindles.
"For those who are sleep-deprived, a short nap, even on a train (but preferably in a semi-recumbent or recumbent position), can be helpful, even if one only gets into the lighter stages of sleep," said Dr. Phyllis Zee, director of the sleep disorders clinic at Northwestern University Medical Center. "It is still an opportunity to dissipate the mounting sleep pressure in the brain. So, even short 20-minute naps have been found to improve performance."
While experts say every person's sleep patterns and needs vary greatly, mid-day power naps can be very restorative for some people. Experts say the power nap gives the body just enough time to rejuvenate, but not enough time to get into deeper stages of sleep, which can leave people groggy when they wake up and try to go about the rest of their day.
"Much depends on what time of day the short sleep occurs [and] how close to the morning wake up time," said Rosalind Cartwright, chairman of psychology at Rush University Medical Center in Chicago. "If the few winks occur in the morning after a less than adequate night and the duration is only 5 minutes, that might feel pretty good as the continuation of light sleep natural to the end of the night. If the sleep occurs later in the afternoon it would probably be less restful as it would by then want to go on down to deep sleep and feel deprived of cycling down into delta sleep."
Delta sleep, or stage 3, is defined as slow-wave, or deep, sleep. It is the stage that night terrors and sleepwalking can take place. Stage 4, or Rapid Eye Movement (REM) sleep, occurs about 90 minutes after people have gone to bed each night and makes up about a quarter of nighttime sleep for most adults. Most dreaming occurs during this stage and some studies have shown that REM sleep is higher during certain learning periods in children.
Experts say the deep sleep usually only makes people feel restored during nighttime sleep, not midday.
"It is important to acquire deep sleep during the night because this stage of sleep has been shown to be more restorative for metabolic and cardiovascular function, as well as for learning and memory," said Zee.
A certain amount of relaxation must be acquired to reach the deeper stages of sleep. While sleep on a train or bus may allow for stage 1 or 2, being on public transportation makes many feel heightened anxiety, which would normally block the body's ability to reach later stages of sleep.
"Comfort levels come into play here," said Kohler. "A lot has to do whether we feel protected and safe. The mind can act as a guard that will try to keep you awake if it feels it needs to protect you, so a fragile or strange environment can reduce the ability to get a restful sleep on one's commute."