Tag Archives: Sleep deprivation

Chronotypes: Sleep “Fingerprints,” “Social Jet Lag,” and Health

-*Are you out of sync with socially-defined time at work and home?

Most people require about one hour of sleep for every two hours awake, and each hour of missed sleep results in deeper sleep until the “sleep debt” is resolved.
Health and safety problems of varying severity ensue when the sleep debt is unresolved.

Till Roenneberg

Till Roenneberg

Till Roenneberg of Ludwig-Maximilians-University Munich investigated these health consequences by studying variances individual sleep “chronotypes,” or the amount of elapsed time until a person reaches midsleep,”  the midpoint between average bedtime when not determined by schedule requirements and waking time.

His Internal Time: Chronotypes, Social Jet Lag, and Why You’re So Tired reported one less-known health consequence of discrepant chronotypes – greater likelihood of smoking. Internal Time
Roenneberg found that greater than 60 percent of those with more than five hours social jet lag are smokers and they have greater difficulty changing this habit than those with less social jet lag.

David Randall

David Randall

Journalist David K. Randall experienced an episode of sleepwalking and documented his quest to learn more about sleep in his Dreamland: Adventures in the Strange Science of Sleep.
In it, he points out that sleep is crucial for muscle regeneration and long-term memory formation, and conversely, sleep loss interferes with these critical functions.

Other negative consequences of sleep disruption are even more dire.Dreamland
He reported that depression rates are forty times higher for people with insomnia than those without sleep problems, and that sleep apnea causes 38,000 fatal heart attacks and strokes in the United States each year.

The difference between the personal chronotype and socially-defined time can be considered “social jet lag” that can lead to chronic exhaustion.
Roenneberg calculates that more than 40 percent of the Central European population experiences more than two hours of social jet lag, which can lead to increased errors at work and in operating equipment like automobiles. These consequences can be critical when the work involves public safety in transportation and health care settings.

Adolescents generally experience considerable social jet lag because their average midsleep point is later than that of many adults, and is incompatible with typical school start times.
This is because typical adolescent brains release the hormone melatonin around eleven o’clock at night until after the seasonal sunrise.
In contrast, adults, who set school schedules, have minimal levels of melatonin in their bodies when they wake in the morning, so they are more likely to feel and act alert in the early morning.

Sleep, then, has both physiological and cultural determinants, as Roenneberg showed in his analysis of agrarian areas which may not have such technologies as electric lighting, Day Light Saving Time, or work-related reasons for early rising.
These people typically go to sleep earlier and awake earlier than urban dwellers, and have significantly different midsleep points than people in cities.

A. Roger Ekirch

A. Roger Ekirch

Historian A. Roger Ekirch of Virginia Polytechnic Institute and State University argues in At Day’s Close: Night in Times Past, that before the Industrial Revolution, the typical sleep pattern was “segmented sleep” (also known as divided sleep, bimodal sleep pattern, or interrupted sleep).

People slept for two or more periods (called “first sleep” or “dead sleep” and “second sleep” or “morning sleep”) in medieval England, punctuated by a period of wakefulness.
Similar terms are found in terms French and Italian languages and among the Tiv of Nigeria.

At Days CloseHe argues that this is the natural pattern of human sleep, and is important in regulating stress.
If this is accurate, it would change western medical diagnosis of sleep disorders and might change expectations of “normal” sleep patterns for optimal health and productivity.

Ekirch’s review of historical records suggests that agrarian people were exhausted after field labor, so they would eat and go to sleep quickly after stopping work.
They would later awaken later to pray, reflect, have sex, perform manual labor, interpret dreams, visit neighbors, or engage in petty crime.
Scholars, in contrast, used this time for loftier pursuits –  to write without interruption.

-*How do you manage segmented sleep and social jet lag?

Related post:
Kept Up at Night by Intrusive Thoughts of Work: Elusive Sleep

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Kept Up at Night by Intrusive Thoughts of Work: Elusive Sleep

According to the US Center for Disease Control, about 70 million Americans have some type of sleep disorder, and I noticed this when colleagues in three different meetings discussed their variations of disrupted sleep.
One person described waking up in the middle of the night with “brain whirlies,” whereas others reported waking up with anxiety about Excel spreadsheet accuracy.

William Dement

William Dement

Many people are familiar with William Dement’s ground-breaking studies of REM and NREM sleep, sleep “architecture”, sleep disorders as the Director of Stanford University Sleep Research Center, and many may know of his research on sleep deprivation’s impact on mood, immune system functioning, work productivity and even public safety.

In fact, he asserts that 33% of traffic accidents and most all major industrial accidents are related to human error based on sleep deprivation.
Dement also shows the relationship between sleep apnea and heart disease and stroke.

He outlined his research and advocacy in The Promise of Sleep: A Pioneer in Sleep Medicine Explores the Vital Connection Between Health, Happiness, and a Good Night’s Sleep 

Test your Sleep Savvy with his questionnaire by answering the following statements with “true” or “false”:

  1. Depriving people of dreams causes mental illness.
  2. Drowsiness, that feeling when the eyelids are trying to close and we cannot keep them open, is the first step and not the last step before we fall asleep.
  3. Generally, people need to sleep one hour for every two hours awake.
  4. Insomnia is a disease.
  5. The purpose of sleep is to rest the body, especially the muscles.
  6. Although sleep needs vary, people who sleep about eight hours, on average, tend to live longer.
  7. If you are well rested, it should take about five to ten minutes to fall asleep.
  8. The single symptom most frequently found in all severe sleep disorders is daytime fatigue.
  9. Sleep gets lighter and more fragmented as we age.
  10. We know what sleep is for, how it works, and how it affects us on a cellular level.

1,2,4,5,7,10 are false
3,6,8,9 are true

Rosalind Cartwright

Rosalind Cartwright

Fewer people may be aware of Dement’s mentor, Rosalind Cartwright, who founded the first accredited Sleep Disorder Service in Illinois in 1978 and wrote The Twenty-four Hour Mind: The Role of Sleep and Dreaming in Our Emotional Lives 

She amplified Dement’s linkage of sleep hygiene with normal mood when she noted that sleep dampens negative emotions “so the next day begins with a calmer frame of mind with which to face the waking world.”

Cartwright recommends behavior modifications to “reclaim healthy sleep” and suggests a three-week “sleep camp” including:

  • Evaluating  risk of sleep disorders
  • Managing sleep “crises”
  • Keeping a sleep diary
  • Measuring  sleep debt

Echoing  the encouragement that “there’s an app for that,” technologists have summarized the most highly-rated Sleep Apps to measure sleep architecture , quality, and duration, and  recommend possible behavioral changes to improve sleep quality and related daily experience:

-*What helps you optimize your sleep experience?
-*Which “sleep myths” do you think are NOT myths?

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