Clocks in action [Elektronische Ressource] : exploring the impact of internal time in real life / vorgelegt von Céline Vetter

Céline Vetter

Sujets

• Psychologie

Informations

• Publié par: ludwig-maximilians-universitat_munchen
• Publié le: 01 janvier 2010
• Nombre de lectures: 26
• Langue: English
• Poids de l'ouvrage: 15 Mo

Extrait

Clocks in Action

Exploring the impact of
internal time in real life



Céline Vetter



Inaugural-Dissertation

zur Erlangung des Doktorgrades

der Philosophie an der Fakultät für Psychologie der
Ludwig-Maximilians-Universität

München



Vorgelegt von

Céline Vetter
aus München

München, 7.Oktober 2010




























Erstgutachter: Prof. Dr. Rainer Schandry

Zweitgutachter: Prof. Dr. Till Roenneberg, Prof. Dr. Gisela Grupe

Tag der mündlichen Prüfung: 3. Februar 2011


Table of Contents
1. GENERAL INTRODUCTION 8
1.1. THE CIRCADIAN CLOCK 9
1.1.1. A BRIEF HISTORY OF CLOCK RESEARCH 9
1.1.2. THE SUPRA-CHIASMATIC NUCLEUS (SCN) 11
1.1.3. SLEEP AND WAKE BEHAVIOUR 13
1.1.4. ENTRAINMENT 16
1.1.5. ZEITGEBER 19
1.1.6. CHRONOTYPE 23

1.2. THE CIRCADIAN CLOCK IN REAL LIFE 25
1.2.1. SOCIAL JETLAG 26
1.2.2. SHIFT WORK 27
1.2.3. ASSESSING CHRONOTYPE IN FIELD STUDIES 28

1.3. SCOPE OF THE RESEARCH 31

2. LIGHTS ON: TRACKING THE EFFECTS OF BLUE-ENRICHED LIGHT
ON SLEEP, ACTIVITY AND WELLBEING IN OFFICE WORKERS 34
2.1. INTRODUCTION 34
2.1.1. THE EFFECT OF LIGHT ON HUMANS: LABORATORY STUDIES 35
2.1.2. THE INFLUENCE OF LIGHT IN OFFICE SETTINGS 37
2.1.3. RESEARCH AIM 37

2.2. MATERIALS AND METHODS 39
2.2.1. STUDY DESIGN 40
2.2.2. PARTICIPANTS 41
2.2.3. MATERIALS 42
2.2.4. DATA PROCESSING 43
2.2.5. STATISTICAL ANALYSES 45

2.3. RESULTS 46
2.3.1. SLEEP AND WAKE BEHAVIOUR 46
2.3.2. LOCO-MOTOR ACTIVITY 48
2.3.3. WELLBEING 51

2.4. DISCUSSION 53

3. VALIDATING THE GOLDEN STANDARD IN THE FIELD:
MEASURING PSYCHOMOTOR VIGILANCE IN ROTATING SHIFT
WORKERS 57
3.1. INTRODUCTION 57
3.1.1. THE PSYCHOMOTOR VIGILANCE TEST (PVT) IN LABORATORY STUDIES 58
3.1.2. PVT PERFORMANCE IN SHIFT WORKERS 62
3.1.3. RESEARCH AIMS 66

3.2. MATERIALS AND METHODS 68
3.2.1. STUDY DESIGN 68
3.2.2. PARTICIPANTS 69
3.2.3. MATERIALS 71
3.2.4. PSYCHOMOTOR VIGILANCE TEST (PVT) 71
3.2.5. PROCEDURE 73
3.2.6. DATA PROCESSING 74
3.2.7. STATISTICAL ANALYSES 75

3.3. RESULTS 76
3.3.1. GENERAL PVT PERFORMANCE 76
3.3.2. PVT PERFORMANCE AS A FUNCTION OF INTERNAL AND EXTERNAL TIME 77
3.3.3. PVT PERFORMANCE AND TIME AWAKE 78
3.3.4. SLEEP DURATION AND ITS EFFECT ON PVT PERFORMANCE 82

3.4. DISCUSSION 83

4. TIME-OF-DAY EFFECTS IN TASK SWITCHING PERFORMANCE: A
FUNCTIONAL MAGNETIC RESONANCE IMAGING STUDY 90
4.1. INTRODUCTION 90
4.1.1. THE TASK SWITCHING PARADIGM: THEORY AND NEURAL CORRELATES 91
4.1.2. TIME-OF-DAY EFFECTS IN TASK SWITCHING PERFORMANCE 95
4.1.3. RESEARCH AIM 97

4.2. MATERIALS AND METHODS 99
4.2.1. STUDY DESIGN 99
4.2.2. PARTICIPANTS 100
4.2.3. PROCEDURE 101
4.2.4. MATERIALS 101
4.2.5. TASK SWICHTING PARADIGM 103
4.2.6. FMRI IMAGE ACQUISITION 105
4.2.7. DATA PROCESSING 105
4.2.8. STATISTICAL ANALYSES 107

4.3. RESULTS 111
4.3.1. MCTQ VALIDATION 111
4.3.2. KAROLINSKA SCALE 112
4.3.3. REACTION TIMES 112
4.3.4. TIME-OF-DAY EFFECTS IN THE TASK SWITCHING NETWORK 114
4.3.5. THALAMIC ACTIVATION, REACTION TIMES AND THE HOMEOSTAT 119

4.4. DISCUSSION 122

5. GENERAL CONCLUSIONS 130

6. ACKNOWLEGMENTS 137

7. DEUTSCHE ZUSAMMENFASSUNG 140

8. CURRICULUM VITAE 147

9. REFERENCES 148

10. APPENDIX 186












So schwer mir das Aufwachen fiel, so schwer fiel mir das Einschlafen.
Ich war noch nicht fertig mit dem Tag, wenn die Nacht übergriff.
Ich war noch nicht fertig mit der Nacht, wenn der Tag aufkam.
Eigentlich hetzte mich immer die Sonne.
Martin Walser, Halbzeit







































1. General Introduction
1. General Introduction

He wakes up every morning, to perpetually re-live every minute of the same day again, and again.
Every morning, the alarm wakes him at 6 a.m. Every morning, he showers, has coffee. And is
forced to re-live the “Groundhog Day”, a festivity celebrated in Pennsylvania - until he can break
rdthe curse and finally pursue a new, better life on 3 of February.
“The Groundhog Day” with Bill Murray (1993)

The exaggeration of a cruel time loop used in the movie “Groundhog Day” builds
up a nightmare of never-ending repetitions. But in its exaggeration , it also
illustrates the temporal structure humans are living in. Those temporal structures
of our everyday life are not arbitrary, or solely socially determined. A central
pacemaker in the brain (and coupled, so-called “body clocks”) governs cyclic
behaviour, with the most obvious one being sleep and wake behaviour. The
underlying complex, biological system follows its internally generated time frame,
ignorant of watches, alarm clocks and other mechanical time keepers providing us
with the external, social time. This project investigates the role of internal time
(the clock) in real life (in action). Three types of populations were at the core of
the studies: office workers, shift workers and researchers themselves.
The Leitmotiv of this thesis revolves around the translation, the relevance, and
applicability of fundamental research results to real life. Is the reported cyclic
variation in reaction times detectable in noisy factory settings? Is sleep influenced
by lighting conditions in office environments, even if our alarm clock rings at the
same time anyways? If we know that metabolism and brain activity is inter alia
influenced by internal time, is this important for neuro-functional imaging studies?
I will outline the theoretical background of the research before the three studies of
this thesis project are described.



8 1. General Introduction
1.1. The circadian clock
All living organisms, from cynobacteria, yeast, plants and insects, to new-world
apes and humans, are governed in their behaviour and physiology by the
1circadian clock. It has evolved - under selection pressure - to anticipate periodic
changes in our environment (Paranjpe & Kumar Sharma, 2005): over the year,
seasons change and with them, vital resources vanish or re-appear and day length
varies. Within 24 hours, the lighting and temperature of the surrounding
environment changes dramatically. Predators (from bacteria to crocodiles) have
specific hunting times and activity profiles. The circadian clock (lat. circa:
approximately, dies: day) permits an anticipation of cyclic environmental (external)
changes, and in turn, adaptation. Such an endogenous, adaptive mechanism will
lead to an evolutionary advantage, as the organism can benefit from a temporal
ecology (e.g. Daan, 1981), aside from spatial or social ones. This thesis will only
include the notions of circannual (i.e. seasonal) and circadian rhythms. Additional
information about tidal and lunar cycles and their influence on humans has
recently been reviewed by Roenneberg and Foster (2008).

1.1.1. A BRIEF HISTORY OF CLOCK RESEARCH
Over 250 years ago, Christoph Wilhem Hufeland, the medical doctor of J.W. von
Goethe, described a “(…) unit of the chronology of nature”. He was referring to
the period of the 24h earth rotation, supposedly conveyed to all humans on earth.
This unit would be reflected in the cycling of bodily functions (Hufeland, 1797,
cited from ; Lemmer, 2009). This – by then speculative - association between an
external, cyclic signal and the variable functions of living organisms has been
reported even earlier, in 1729, by the French astronomist Jean Jacques de Mairan.
In his chamber, he evicted a mimosa pudica plant from the day and night cycle to
constant darkness. Still, it unfolded its leaves before sunrise and closed it in the
evening hours - as if it was internally orchestrated (de Mairan, 1729).

1 Franz Halberg has coined this term in the scientific, biological language (Lemmer, 2009).
9 1. General Introduction
2In humans, Nathanial Kleitman engaged in a similar procedure as de Mairan. He
lived on a 21h and 28h schedule, investigating the effects on physiology and sleep
and wake behaviour, while secluded from external temporal hints like daylight.
The sleep- and temperature recordings maintained oscillating cycles, pertaining the
existence of an endogenous, self-sustained timing mechanism. Self-sustainability
3today represents one of the major characteristics of the circadian clock . Kleitman
already reported inter-individual differences in the period length