The Hormonal Effects of Cumulative Partial Sleep Deprivation in Healthy Young Men

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The Hormonal Effects of Cumulative Partial Sleep
Deprivation in Healthy Young Men

• MCRTN-CT-2004-512362

• Wessel M.A. van Leeuwen1,2, Mikko Härmä2, and
  Tarja Porkka-Heiskanen1
• 1 University of Helsinki, Institute of
  Biomedicine
• 2 Finnish Institute of Occupational Health, Brain
  and Work Research Centre

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What is sleep?

• Sleep is not a passive state,
• absence of waking
• Sleep consists of several types of brain
  activities NREM and REM
• - electrical activity of the
• brain is measured
• using EEG

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Sleep Architecture
Sleep Research Society 1997
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Is sleep important?

• All known species sleep
• - sleep is dangerous, but still all animals
  choose to sleep
• Extremely long period without sleep kills
• Loss of sleep results in bad performance
• Temporary loss of sleep is compensated for later
  (recovery sleep)

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What happens if we do not sleep?

• Ability to perform is reduced
• - motor performance, memory etc.
• Mood problems (depression)
• Increased stress levels
• Increased risk for diseases
• - cardivascular
• - type II diabetes
• - obesity?

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What is happening to our sleep?

• Epidemiological argument
• - time spent in sleep is diminishing

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How to study the effects of sleep loss?

• Acute Sleep Deprivation
• - short period
• - complete loss
• Chronic Sleep Deprivation
• - longer period
• - partial loss
• - more common form of sleep loss than acute

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Why laboratory experiments?

• Control of environment
• Controlled group of subjects
• Concentrate on defined factors

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Our experiment

• Sleep was restricted to 4 hours per day during 5
  consecutive days

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We measured

• Stress reactive hormones
• - Cortisol saliva
• - Neuropeptide Y saliva
• - Testosterone blood
• Cardiovascular risk factors
• - C-reactive protein blood
• - Homocystein blood

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HPA-axis
NPY
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Introduction Cortisol NPY
NPY
Chronic stress
Adrenal Cortex
Cortisol
Pituitary
damage
Hypothalamus
Hippocampus
Memory
Negative feedback
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Results Cortisol
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Results NPY
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Introduction CRP
Obesity, chronic fatigue, sleep disturbances, etc.
Inflammation
CRP synthesis in liver
Risk of stroke and myocardial infarction
CRP in blood
Removal of toxic molecules
Atherosclerotic lesions
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Results CRP
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Summary of Results
Substance Effect of sleep loss Effect of subsequent Recovery sleep
Cortisol No effect No effect
NPY Decrease No effect
Testosterone Decrease No effect
CRP Increase Increase
Homocystein Increase Decrease
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Conclusion

• Restricting our sleep results in more (chronic)
  stress and a higher risk to develop
  cardiovascular diseases.