The Development of Circadian Rhythms in Human Infants

More documents

Recommendations

Info

Sleep data A further slope based analysis/linear analysis investigating rate of change of sleep parameters could be performed against gestational and „developmental‟ age; as well as sinusoidal curve modelling. Gene expression data The above methods were employed for gene expression data but are not reported on in this thesis due to constraints of space. The use of S curve did not yield positive results. This was expected as the random effects modelling showed no evidence of increase or decrease in gene expression with age. A secondary analysis of the genetic data would involve studying the changes in gene amplitude using ultradian rhythms (4, 6, 8, and 12 hourly) rather than changes over 24 hours, to examine the strength of the rhythms. This would be followed by further work utilising the different amplitudes and R squared values in new random effects models. 240
Summary and Future work This study highlights that the first four months for an infant are crucial and critical to development, maturation and adaptation to an independent life outside of the intrauterine environment and separate from the mother. The rapidity and extent of change may confer increased vulnerability to the infant if challenged by an external adverse factor such as an infection. In summary this research again showed that infants demonstrate an „abrupt‟ change in overnight core body temperature during night time sleep which may be used as a marker of physiological maturity, as shown previously in work by this group. There are obvious changes in infant behaviour and physiology which occur alongside the achievement of a diurnal temperature rhythm (patterns in melatonin secretion, sleep consolidation and a diurnal pattern of peripheral gene expression). Changes in cortisol secretion appear to be an early and important circadian rhythm that develops (pre temperature maturity) which may act as a trigger or act as a catalyst or key to the development of other circadian rhythms. As suggested by previous work and further supported by this study, although the order of development in general stays the same, the timing of the maturation may be different for individuals (infants in this case). The same physiological events give rise to physiological maturity at different ages in different babies. Developmental periods which have been studied more extensively such as prenatal growth and development and puberty have given clear examples of development being ordered, sequential and universal. This study opens the door to several lines of 241
Page 1 and 2:
The Development of Circadian Rhythm
Page 3 and 4:
Table of Contents LIST OF FIGURES .
Page 5 and 6:
7.1 Analysis of infant sleep measur
Page 7 and 8:
List of Figures Figure 1.1 - Diagra
Page 9 and 10:
List of Tables Table 3.1 - Descript
Page 11 and 12:
1 Introduction Happiness is not a m
Page 13 and 14:
Each of these independently is impo
Page 15 and 16:
There is general agreement, that al
Page 17 and 18:
Summary 1. Development encompasses
Page 19 and 20:
Figure 1.1 - Diagram illustrating c
Page 21 and 22:
A phase shift is used to describe a
Page 23 and 24:
1.4 Ontogeny in Human Infants Well
Page 25 and 26:
1.5.2 Circadian Rhythms in Temperat
Page 27 and 28:
1.5.4 Factors affecting Temperature
Page 29 and 30:
1.6 Melatonin (Reviewed in Cardinal
Page 31 and 32:
mechanism by which this occurs is n
Page 33 and 34:
It is at this time that infant slee
Page 35 and 36:
1.7 Cortisol Cortisol is a hormone,
Page 37 and 38:
1.7.3 Circadian pattern of Cortisol
Page 39 and 40:
In a separate study, Weerth et al u
Page 41 and 42:
Summary 1. Cortisol is crucial to a
Page 43 and 44:
NREM sleep has 4 stages. It occupie
Page 45 and 46:
1.8.1 Functions of Sleep The functi
Page 47 and 48:
1.8.3 Ontogeny of Sleep in Infants
Page 49 and 50:
Sleep can clearly be used as marker
Page 51 and 52:
For the purpose of this study, the
Page 53 and 54:
Summary 1. Sleep is defined by lack
Page 55 and 56:
Overall the SCN generates signals (
Page 57 and 58:
Figure 1.2 - The mammalian circadia
Page 59 and 60:
1.9.3 Molecular Components of the C
Page 61 and 62:
Figure 1.3 - Mechanisms from SCN to
Page 63 and 64:
1.9.7 Melatonin and Clock Melatonin
Page 65 and 66:
The links between the central clock
Page 67 and 68:
Chapter 2 Methods
Page 69 and 70:
There were strict inclusion and exc
Page 71 and 72:
This personal contact on the postna
Page 73 and 74:
2.1.3 Home monitoring visits The fi
Page 75 and 76:
2.1.4 Further monitoring informatio
Page 77 and 78:
Core body temperature was taken sim
Page 79 and 80:
2.3 Collection of urine samples Pai
Page 81 and 82:
were read against air at 429 nm aft
Page 83 and 84:
allowed the display and comprehensi
Page 85 and 86:
2.8.1 RNA preparation and cDNA synt
Page 87 and 88:
In total three methods were trialle
Page 89 and 90:
2.11 Statistical methods For compar
Page 91 and 92:
test that each infant‟s height an
Page 93 and 94:
Power calculation Sample size: Fift
Page 95 and 96:
3 Results 3.1 Recruited subjects an
Page 97 and 98:
predominantly affluent areas of the
Page 99 and 100:
Birth history and past medical hist
Page 101 and 102:
3.1.3 Socioeconomic demographics of
Page 103 and 104:
her best friend losing her battle w
Page 105 and 106:
Sleep environment of infants All mo
Page 107 and 108:
Summary 1. This study had higher ra
Page 109 and 110:
4 Results 4.1 Core body temperature
Page 111 and 112:
Degrees Celsius 36.70 36.60 36.50 3
Page 113 and 114:
11-13 weeks There is no significant
Page 115 and 116:
Core body temperature (degrees Cels
Page 117 and 118:
Number of infants 10 8 6 4 2 0 7 8
Page 119 and 120:
Mean minimum rectal temperature in
Page 121 and 122:
Mean minimum rectal temperature in
Page 123 and 124:
Figure 4.7 shows the changes in the
Page 125 and 126:
Chapter 5 Result
Page 127 and 128:
4 or 6 hourly samples. Circadian rh
Page 129 and 130:
Figure 5.1 - Distribution of mean n
Page 131 and 132:
5.1.2 Emergence of diurnal rhythm f
Page 133 and 134:
Figure 5.3 - Histogram showing dist
Page 135 and 136:
Figure 5.4 - Changes in night time
Page 137 and 138:
Night-day difference in melatonin s
Page 139 and 140:
Summary 1. There is an increase in
Page 141 and 142:
6 Results DESCRIPTION OF THE URINAR
Page 143 and 144:
Page 145 and 146:
6.1.2 Emergence of diurnal rhythm f
Page 147 and 148:
Figure 6.3 - Histogram showing dist
Page 149 and 150:
Page 151 and 152:
Cortisol values were corrected to a
Page 153 and 154:
6.1.4 Relationship between night an
Page 155 and 156:
Chapter 7 Results
Page 157 and 158:
Mean Length of Sleep/ Wake Bouts Th
Page 159 and 160:
Sleep parameters were recorded as m
Page 161 and 162:
7.3 Development of infant sleep rel
Page 163 and 164:
Figure 7.2 - Changes in infant slee
Page 165 and 166:
Figure 7.4 - Changes in percentage
Page 167 and 168:
Figure 7.5 - Changes in infant frag
Page 169 and 170:
Figure 7.7 - Changes in number of m
Page 171 and 172:
Figure 7.9 - Changes in the percent
Page 173 and 174:
Sleep efficiency (%) 100.0 90.0 80.
Page 175 and 176:
Chapter 8 Results
Page 177 and 178:
Considering only those weeks of mea
Page 179 and 180:
8.2 Description of peripheral gene
Page 181 and 182:
18:30 hours 0.9927; 01:00 ours 1.01
Page 183 and 184:
The weeks after temperature maturat
Page 185 and 186:
Further peripheral gene graphical r
Page 187 and 188:
Raw data points are represented by
Page 189 and 190:
H3f3b/Gap H3f3b/Gap H3f3b/Gap H3f3b
Page 191 and 192:
8.3 Detailed gene expression analys
Page 193 and 194:
Summary 1. H3f3b was selected as ge
Page 195 and 196:
9 Results FACTORS AFFECTING SLEEP A
Page 197 and 198:
Care and infant related factors �
Page 199 and 200: Table 9.3 - Effect of family occupa
Page 201 and 202: * Class 7 used as reference group
Page 203 and 204: Table 9.6 - Effect of measured infa
Page 205 and 206: Summary: 1. A mature physiological
Page 207 and 208: 10 Results 10.1 Circadian rhythms -
Page 209 and 210: value of above 0.5 for R squared wa
Page 211 and 212: Table 10.1 - Temporal relationship
Page 213 and 214: Chapter 11 Discussion
Page 215 and 216: � What if any are the factors whi
Page 217 and 218: 11.1 Physiological development - ag
Page 219 and 220: There are other proven factors whic
Page 221 and 222: drawbacks of the spread of data - a
Page 223 and 224: presented in table 6.1 do not have
Page 225 and 226: separate methods were applied to th
Page 227 and 228: significant. Sleep latency was cons
Page 229 and 230: The function of sleep in developmen
Page 231 and 232: Melatonin secretion was higher on n
Page 233 and 234: In this study sleeping in the same
Page 235 and 236: Timing of sleep maturation was diff
Page 237 and 238: systematic, ordered developmental p
Page 239 and 240: individual gene plots that provide
Page 241 and 242: temperature recording devices adapt
Page 243 and 244: Both melatonin and cortisol rhythms
Page 245 and 246: Extension of this period of monitor
Page 247 and 248: Second, we demonstrated the gene of
Page 249: Cortisol and melatonin Slope based
Page 253 and 254: � Maximise technique for measurin
Page 255 and 256: “There is a science of infant car
Page 257 and 258: References
Page 259 and 260: Bajanowski, T., Vege, Å., Byard, R
Page 261 and 262: Chamley, C.A., Carson P, Randall D,
Page 263 and 264: Frank, M.G., Heller, H.C., 2003. Th
Page 265 and 266: intrahypothalamic administration of
Page 267 and 268: Mirmiran, M. & Ariagno, R.L., 2000.
Page 269 and 270: Rawson, D., Petersen, S.A., Wailoo,
Page 271 and 272: Stokkan, K.A., Yamazaki, S., Tei, H
Page 273 and 274: Winter, J.S.D., 1985. The adrenal c
show all

The Development of Circadian Rhythms in Human Infants

Create successful ePaper yourself

Delete template?

Save as template?