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

Wessel M.A. van LeeuwenWessel M.A. van Leeuwen1,21,2, Mikko , Mikko HärmäHärmä22, and Tarja Porkka-Heiskanen, and Tarja Porkka-Heiskanen11

11 University of Helsinki, Institute of University of Helsinki, Institute of BiomedicineBiomedicine2 2 Finnish Institute of Occupational Health, Finnish Institute of Occupational Health, Brain and Work Research CentreBrain and Work Research Centre

MCRTN-CT-2004-512362

What is sleep?What is sleep?

Sleep is Sleep is notnot a passive state, a passive state,

absence of wakingabsence of waking

Sleep consists of several types of brain Sleep consists of several types of brain activities: NREM and REMactivities: NREM and REM

- electrical activity of the - electrical activity of the

brain is measured brain is measured

using EEGusing EEG

Sleep Research Society 1997

Sleep ArchitectureSleep Architecture

Is sleep important?Is sleep important?

All known species sleepAll known species sleep

- sleep is dangerous, but still all - sleep is dangerous, but still all animals choose to sleepanimals choose to sleep

Extremely long period without sleep Extremely long period without sleep killskills

Loss of sleep results in bad Loss of sleep results in bad performanceperformance

Temporary loss of sleep is Temporary loss of sleep is compensated for later (=recovery compensated for later (=recovery sleep)sleep)

What happens if we do What happens if we do not sleep?not sleep?

Ability to perform is reducedAbility to perform is reduced- motor performance, memory etc.- motor performance, memory etc.

Mood problems (depression)Mood problems (depression) Increased stress levelsIncreased stress levels Increased risk for diseasesIncreased risk for diseases

- cardivascular- cardivascular- type II diabetes- type II diabetes- obesity?- obesity?

What is happening to What is happening to our sleep?our sleep? Epidemiological argumentEpidemiological argument

- time spent in sleep is diminishing- time spent in sleep is diminishing

How to study the effects How to study the effects of sleep loss?of sleep loss?

Acute Sleep DeprivationAcute Sleep Deprivation

- short period- short period

- complete loss- complete loss Chronic Sleep DeprivationChronic Sleep Deprivation

- longer period- longer period

- partial loss- partial loss

- more common form of sleep loss than - more common form of sleep loss than acuteacute

Why laboratory Why laboratory experiments?experiments?

Control of environmentControl of environment

Controlled group of subjectsControlled group of subjects

Concentrate on defined factorsConcentrate on defined factors

Our experimentOur experiment

Sleep was restricted to 4 hours Sleep was restricted to 4 hours per day during 5 consecutive per day during 5 consecutive daysdays

19 20 21 22 23 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18TUE arrival baseline day 1WED baseline day 2THU sleep debt day 1FRI sleep debt day 2SAT sleep debt day 3SUN sleep debt day 4MON sleep debt day 5TUE recovery day 1WED recovery day 2THU departure

19 20 21 22 23 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18TUE arrival baseline day 1WED baseline day 2THU sleep debt day 1FRI sleep debt day 2SAT sleep debt day 3SUN sleep debt day 4MON sleep debt day 5TUE recovery day 1WED recovery day 2THU departure

We measured:We measured:

Stress reactive hormonesStress reactive hormones

- Cortisol- Cortisol salivasaliva

- Neuropeptide Y- Neuropeptide Y salivasaliva

- Testosterone- Testosterone bloodblood Cardiovascular risk factorsCardiovascular risk factors

- C-reactive protein- C-reactive protein bloodblood

- Homocystein- Homocystein bloodblood

NPY

HPA-axisHPA-axis

Introduction: Cortisol & Introduction: Cortisol & NPY NPY

Cortisol

Hippocampus

Hypothalamusdamage

Negative feedback

Chronic stress

Memory

NPY

PituitaryAdrenal Cortex

0

5

10

15

20

25

30

35

40

45

6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00

Time of the day

Co

rtis

ol (

nm

ol/l

)

baseline

sleep deprived

recovery

Results: CortisolResults: Cortisol

0.00

0.50

1.00

1.50

2.00

2.50

3.00

6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00

Time of the day

NP

Y (

ng

/ml)

baseline

sleep deprived

recovery

Results: NPYResults: NPY

Introduction: CRPIntroduction: CRP

Inflammation CRP synthesis in liver

CRP in blood

Removal of toxic molecules

Obesity, chronic fatigue, sleep disturbances, etc.

Atherosclerotic lesions

Risk of stroke and myocardial infarction

Sleep Deprivation and CRP

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Baseline Sleep deprived Recovery

Experimental day

CR

P (

mg

/l) Baseline

Sleep deprived

Recovery

Results: CRPResults: CRP

Summary of ResultsSummary of Results

SubstanceSubstance Effect of Effect of

sleep losssleep lossEffect of Effect of subsequentsubsequent

Recovery sleepRecovery sleep

CortisolCortisol No effectNo effect No effectNo effect

NPYNPY DecreaseDecrease No effectNo effect

TestosteroneTestosterone DecreaseDecrease No effectNo effect

CRPCRP IncreaseIncrease IncreaseIncrease

HomocysteinHomocystein IncreaseIncrease DecreaseDecrease

ConclusionConclusion

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