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Naomi L Rogers

Publications and source records attributed to Naomi L Rogers.

13 recordsLinked to original sources
PubMed2007

Thermoregulatory changes around the time of sleep onset.

A causal relationship between declining nocturnal core temperature, increasing peripheral temperature, and sleep onset has been reported. The exact trigger for these thermoregulatory changes around sleep onset, however, is unknown. Our aim was to examine one possible trigger: prior knowledge of bedtime. Fourteen young, healthy male subjects (mean age+/-sem: 21.9+/-0.6 years), participated in a randomized, single-blind crossover study, where knowledge of bedtime was manipulated. Following a baseline night, subjects completed three experimental nights: (A) aware of bedtime; (B) no knowledge of bedtime; (C) misinformed about bedtime. In all conditions lights were turned off at each subject's habitual bedtime (determined from sleep diaries), to individually standardize the time of lights off. Polysomnography, rectal and peripheral (foot) temperatures were recorded continuously on each night. There was no significant difference in the time of sleep onset among conditions (mean+/-s.d.: 11:55 h+/-0.73 min), and in all conditions sleep onset occurred at the same rectal temperature. A significant difference in the temperature gradient between rectal and peripheral temperatures among the conditions was evident from 90 min to 40 min prior to sleep onset (P=0.05), with subjects achieving a more rapid rate of temperature change in the B and C condition relative to condition A. The present findings suggest that knowledge of bedtime may modulate changes in temperature around the time of sleep onset. It appears that there is an optimal core body temperature at which to initiate sleep, and changes in the rate of peripheral heat loss may assist in achieving this optimal temperature, and hence facilitate sleep onset.

Adult↗
PubMed2006

Effects of short-term CPAP withdrawal on neurobehavioral performance in patients with obstructive sleep apnea.

STUDY OBJECTIVE: Changes in sleep parameters and neurobehavioral functioning were systematically investigated after an acute (1 night) and short-term (7 nights) period of withdrawal from continuous positive airway pressure (CPAP) treatment and 1 subsequent night of CPAP reintroduction in patients with obstructive sleep apnea. DESIGN: Repeated-measurement within-subject design. SETTING: Sleep laboratory, university teaching hospital. PARTICIPANTS: Twenty participants receiving optimal CPAP therapy for > or = 12 months. INTERVENTIONS: CPAP withdrawal. MEASUREMENTS AND RESULTS: Polysomnograms were performed on Night 0 (with CPAP), Night 1 and Night 7 (without CPAP) and Night 8_R (with CPAP). Acute CPAP withdrawal resulted in the recurrence of sleep-disordered breathing with sleep disruption, hypoxemia, and increased subjective sleepiness. Short-term CPAP withdrawal exacerbated hypoxemia, increased subjective and objective sleepiness and poor mood ratings. Neurobehavioral functioning assessed using the Psychomotor Vigilance Task was impaired following Night 7 and associated with hypoxemia and changes in morning levels of tumor necrosis factor-alpha. However, other neurobehavioral measures were not affected. Autonomic arousals measured via respiratory-related reductions in finger blood volume by peripheral arterial tonometry decreased from Night 1 to Night 7. On Night 8_R, reintroduction of CPAP treatment eliminated most airway obstruction, maintained oxygenation, and reversed daytime sleepiness and some vigilance decrements. CONCLUSION: Despite recurrence of sleep-disordered breathing with increased sleepiness and impaired vigilance, most neurobehavioral variables were unaffected by CPAP withdrawal. The reduction in vigilance appeared to be associated with worsened hypoxemia and changed levels of tumor necrosis factor-alpha. Resumption of CPAP treatment had immediate benefits on sleep consolidation and subjective sleepiness.

Body Mass Index↗
PubMed2006

Assessment of sleep in women with night eating syndrome.

STUDY OBJECTIVES: Evaluation of sleep in subjects with night eating syndrome (NES). DESIGN: Polysomnographic and questionnaire comparisons between subjects with NES and controls. SETTING AND PARTICIPANTS: Fifteen women with NES (mean +/- SD = 41 +/- 8 years) and 14 women (comparable age and weight) without NES (39 +/- 10 years) were studied in the laboratory for 3 days. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Subjects with NES did not differ from controls in timing of sleep onset or offset. They had less stage 2 sleep than controls (minutes, p = .012; percentage, p = .016) and less stage 3 sleep (p = .023), which contributed to their having a lower total sleep time (p = .05) and reduced sleep efficiency (p = .03). Subjects with NES did not have more awakenings than controls, but 93.3% of them ate on awakening during all 3 nights, while 92.9% of controls did not eat on any night. Logistic discriminant analyses identified a multiple sleep parameter model associated with increased likelihood of NES that had sensitivity of 84.6% and specificity of 76.9%. Patients with NES were more depressed than controls (p < .001) and reported greater sleep disturbance that included lower sleep quality (p < or = .001), reduced sleep duration (p < or = .001), and increased number of awakenings (p < or = .001). CONCLUSIONS: Patients with NES appear to have sleep maintenance insomnia rather than sleep-related eating disorder or a parasomnia. The maintenance of normal timing for sleep-wake behavior in the presence of a phase delay in the timing of caloric intake suggests this disorder reflects a state of internal circadian desynchrony associated with significant sleep complaints. It remains unknown whether the sleep disturbance precedes the abnormally timed eating.

Adult↗
PubMed2005

Caffeine: implications for alertness in athletes.

Caffeine is one of the most widely consumed drugs in the world, taken socially and for its alertness- and performance-promoting actions. Extensive reports assert that caffeine increases alertness and cognitive performance levels and, when taken before exercise, demonstrates ergogenic properties. Caffeine ingestion has been associated with increased performance during endurance submaximal, and acute, high-intensity exercise. The exact mechanism of action for the performance effects of caffeine is unknown, although several physiologically and psychologically based theories exist as to how caffeine achieves increased performance capabilities. This paper outlines the known sites of caffeine activity in the body,and discusses these with respect to the effects of caffeine observed during performance assessments.

Analgesia↗
PubMed2005

Optical computer recognition of facial expressions associated with stress induced by performance demands.

Application of computer vision to track changes in human facial expressions during long-duration spaceflight may be a useful way to unobtrusively detect the presence of stress during critical operations. To develop such an approach, we applied optical computer recognition (OCR) algorithms for detecting facial changes during performance while people experienced both low- and high-stressor performance demands. Workload and social feedback were used to vary performance stress in 60 healthy adults (29 men, 31 women; mean age 30 yr). High-stressor scenarios involved more difficult performance tasks, negative social feedback, and greater time pressure relative to low workload scenarios. Stress reactions were tracked using self-report ratings, salivary cortisol, and heart rate. Subjects also completed personality, mood, and alexithymia questionnaires. To bootstrap development of the OCR algorithm, we had a human observer, blind to stressor condition, identify the expressive elements of the face of people undergoing high- vs. low-stressor performance. Different sets of videos of subjects' faces during performance conditions were used for OCR algorithm training. Subjective ratings of stress, task difficulty, effort required, frustration, and negative mood were significantly increased during high-stressor performance bouts relative to low-stressor bouts (all p < 0.01). The OCR algorithm was refined to provide robust 3-d tracking of facial expressions during head movement. Movements of eyebrows and asymmetries in the mouth were extracted. These parameters are being used in a Hidden Markov model to identify high- and low-stressor conditions. Preliminary results suggest that an OCR algorithm using mouth and eyebrow regions has the potential to discriminate high- from low-stressor performance bouts in 75-88% of subjects. The validity of the workload paradigm to induce differential levels of stress in facial expressions was established. The paradigm also provided the basic stress-related facial expressions required to establish a prototypical OCR algorithm to detect such changes. Efforts are underway to further improve the OCR algorithm by adding facial touching and automating application of the deformable masks and OCR algorithms to video footage of the moving faces as a prelude to blind validation of the automated approach.

Adult↗
PubMed2004

Circadian eating and sleeping patterns in the night eating syndrome.

OBJECTIVE: To compare the eating and sleep-wake patterns of persons with the night eating syndrome (NES) with those of matched control subjects. RESEARCH METHODS AND PROCEDURES: Forty-six overweight/obese NES subjects (mean age 43.3 +/- 9.8 years; 32 women) and 43 similar controls (mean age 39.0 +/- 11.0 years; 28 women) wore wrist actigraphs for 7 days and completed sleep and food diaries at home. RESULTS: There was no difference between the total energy intake of the NES and the control subjects, but the pattern of energy intake differed greatly. Relative to control subjects, the temporal pattern of food intake of night eaters was delayed. Food intake after the evening meal, as a proportion of the 24-hour intake, was more than 3-fold greater in NES subjects than in controls (34.6 +/- 10.1% vs. 10.0 +/- 6.9%, p = 0.001). NES subjects had sleep onset, offset, and total sleep duration times comparable with those of controls. NES subjects reported more nocturnal awakenings than did controls (1.5 +/- 1.0 per night vs. 0.5 +/- 0.5; p < 0.001), and their actigraphically monitored arousals occurred earlier during sleep (at 128 minutes after sleep onset vs. 193 minutes, p = 0.01). NES subjects consumed food on 74% of the awakenings vs. 0% for the controls. DISCUSSION: The pattern of cumulative energy intake of the night eaters suggests a phase delay in energy consumption relative to sleep-wake times. NES may involve a dissociation of the circadian control of eating relative to sleep.

Activity Cycles↗
PubMed2003

Sleep, waking and neurobehavioural performance.

Waking neurobehavioural or cognitive functioning is largely dependent on two mechanisms both in synchrony and in opposition to each other: the sleep homeostatic and circadian systems. The influences of these systems are particularly evident during periods of sustained wakefulness or sleep deprivation. Although the effects of these two systems on neurobehavioural functioning during periods of extended wakefulness have been demonstrated experimentally, there does not exist an adequate theory to describe the underlying brain mechanisms responsible for these neurobehavioural deficits. Much research has in fact concentrated not on understanding the nature of these deficits, but rather in counteracting them, via the use of countermeasures, such as naps and wake promoting compounds.

Animals↗
PubMed2003

Neurobehavioural performance effects of daytime melatonin and temazepam administration.

Exogenous melatonin is a potential treatment for circadian disruption and insomnia. Hence, it is important to determine and quantify neurobehavioural performance effects associated with its use. The present study compared neurobehavioural performance following administration of melatonin and the benzodiazepine temazepam, using a within-subjects design. Following a training day, 16 healthy, young subjects (six males, 10 females; mean age +/- SEM, 21.4 +/- 6 years) participated in a 3-day protocol. After sleeping overnight in the laboratory, subjects completed a battery of tests at hourly intervals between 08:00 and 11:00 hours and at two hourly intervals between 13:00 and 17:00 hours. The neurobehavioural performance tasks included: unpredictable tracking, spatial memory, vigilance and logical reasoning. Subjective sleepiness was measured at hourly intervals using a visual analogue scale. At 12:00 h subjects were administered a capsule containing 5 mg melatonin, 10 mg temazepam or placebo, in a randomized, double-blind crossover fashion. A significant drug x time interaction was evident on the unpredictable tracking, spatial memory and vigilance tasks (P < 0.05). Greater changes in performance were evident following temazepam administration than melatonin administration, relative to placebo. Administration of melatonin or temazepam significantly elevated subjective sleepiness levels, relative to placebo (P </= 0.05). The present findings demonstrate that melatonin administration induces a smaller deficit in performance on a range of neurobehavioural tasks than temazepam. Given melatonin's soporific and chronobiotic properties, these results suggest that melatonin may be preferable to benzodiazepines in the management of circadian and sleep disorders.

Adult↗
PubMedDate not supplied

Sleep and metabolic control: waking to a problem?

1. The aim of the present review is to outline: (i) the association between sleep and metabolism; (ii) how sleep duration influences the development of disease; and (iii) how sex differences, ageing and obesity may potentially influence the relationship between sleep, metabolic control and subsequent disease. 2. Sleep is associated with a number of endocrine changes, including a change in insulin action in healthy young individuals. Sleep duration shows a prospective U-shaped relationship with all-cause mortality, cardiovascular disease and Type 2 diabetes. 3. Chronic sleep restriction is becoming more common. Experimental sleep restriction impedes daytime glucose control and increases appetite. 4. The sex hormones oestrogen and testosterone influence sleep duration and quality and may account for sex differences in the prevalence of sleep-related disorders. 5. Ageing is associated with a decreased sleep duration, decreased muscle mass and impaired insulin action. 6. Obesity impairs insulin action and is associated with the incidence and severity of obstructive sleep apnoea. 7. Sleep plays an integral role in metabolic control. Consequently, insufficient sleep may represent a modifiable risk factor for the development of Type 2 diabetes. The challenge ahead is to identify how sex differences, ageing and obesity could potentially influence the relationship between sleep and metabolism.

Aging↗