Owls, Larks and Camels


Normal cuts a Wide Swath

by Madelyn Griffith-Haynie, CTP, CMC, ACT, MCC, SCAC
Another article in the Sleep Series

“Early to bed, early to rise,
makes a man stupid and blind in the eyes”

~ Mazer Rackham (from Orson Scott Card‘s book “Ender’s game“)

 

NiteOwlandMoon

Normal Circadian Rhythms

Among people with healthy circadian clocks, there are “Larks” or “morning people” who prefer to sleep and wake early, and there are “Owls” who prefer to go to sleep later each night and awaken much later each day.

But whether they are larks or owls, people with normal circadian systems:

  • can awaken in time for what they need to do in the morning, and fall asleep at night at a time that allows them to get enough sleep before they have to get up.
  • can sleep and wake up at the same time every day, if they want to.
  • will, within a few days of starting a new routine that requires their getting up earlier than usual, start to fall asleep at night earlier.

For example, someone used to sleeping at 1 a.m. and waking up at 9 a.m. begins a new job on a Monday, and must get up at 6 a.m. to get ready for work.

By the following Friday, the person has begun to fall asleep at around 10 p.m., and can wake up at 6 a.m. feeling well-rested.

This adaptation to earlier sleep/wake times is known as ‘advancing the sleep phase.’ Healthy people can advance their sleep phase by about one hour each day.

24 hours a day isn’t “normal”

Researchers have placed volunteers in caves or special apartments for several weeks without clocks or other time cues. Without those time cues, the volunteers tended to go to bed up to an hour later and to get up about an hour later each day.

These experiments demonstrated that the “free-running” circadian rhythm in humans is greater than the earth’s 24 hour cycle – anywhere from 24:15 to 25 or so a day].

To maintain a 24 hour day/night cycle, the biological clock needs regular environmental time cues, for example sunrise, sunset, and daily routine.

Time cues are what keep our body clocks aligned with the rest of the world.

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