Developing neuroimaging phenotypes of the default mode network in PTSD: integrating the resting state, working memory, and structural connectivity

Complementary structural and functional neuroimaging techniques used to examine the Default Mode Network (DMN) could potentially improve assessments of psychiatric illness severity and provide added validity to the clinical diagnostic process. Recent neuroimaging research suggests that DMN processes may be disrupted in a number of stress-related psychiatric illnesses, such as posttraumatic stress disorder (PTSD). Although specific DMN functions remain under investigation, it is generally thought to be involved in introspection and self-processing. In healthy individuals it exhibits greatest activity during periods of rest, with less activity, observed as deactivation, during cognitive tasks, e.g., working memory. This network consists of the medial prefrontal cortex, posterior cingulate cortex/precuneus, lateral parietal cortices and medial temporal regions. Multiple functional and structural imaging approaches have been developed to study the DMN. These have unprecedented potential to further the understanding of the function and dysfunction of this network. Functional approaches, such as the evaluation of resting state connectivity and task-induced deactivation, have excellent potential to identify targeted neurocognitive and neuroaffective (functional) diagnostic markers and may indicate illness severity and prognosis with increased accuracy or specificity. Structural approaches, such as evaluation of morphometry and connectivity, may provide unique markers of etiology and long-term outcomes. Combined, functional and structural methods provide strong multimodal, complementary and synergistic approaches to develop valid DMN-based imaging phenotypes in stress-related psychiatric conditions. This protocol aims to integrate these methods to investigate DMN structure and function in PTSD, relating findings to illness severity and relevant clinical factors.

Coupled Intrinsic Connectivity Distribution analysis: a method for exploratory connectivity analysis of paired FMRI data

We present a novel voxel-based connectivity approach for paired functional magnetic resonance imaging (fMRI) data collected under two different conditions labeled the Coupled Intrinsic Connectivity Distribution (coupled-ICD). Our proposed method jointly models both conditions to incorporate additional paired information into the connectivity metric. Voxel-based connectivity holds promise as a clinical tool to characterize a wide range of neurological and psychiatric diseases, and monitor their treatment. As such, examining paired connectivity data such as scans acquired pre- and post-intervention is an important application for connectivity methodologically. When presented with data from paired conditions, conventional voxel-based methods analyze each condition separately. However, summarizing each connection separately can misrepresent patterns of changes in connectivity. We show that commonly used methods can underestimate functional changes and subsequently introduce and evaluate our solution to this problem, the coupled-ICD metric, using two studies: 1) healthy controls scanned awake and under anesthesia, and 2) cocaine-dependent subjects and healthy controls scanned while being presented with relaxing or drug-related imagery cues. The coupled-ICD approach detected differences between paired conditions in similar brain regions as the conventional approaches while also revealing additional changes in regions not identified using conventional voxel-based connectivity analyses. Follow-up seed-based analyses on data independent from the voxel-based results also showed connectivity differences between conditions in regions detected by coupled-ICD. This approach of jointly analyzing paired resting-state scans provides a new and important tool with many applications for clinical and basic neuroscience research.

Regional homogeneity and resting state functional connectivity: associations with exposure to early life stress

Early life stress (ELS) confers risk for psychiatric illness. Previous literature suggests ELS is associated with decreased resting-state functional connectivity (rs-FC) in adulthood, but there are no studies of resting-state neuronal activity in this population. This study investigated whether ELS-exposed individuals demonstrate resting-state activity patterns similar to those found in PTSD. Twenty-seven adults (14 with at least moderate ELS), who were medication-free and without psychiatric or medical illness, underwent MRI scans during two 4-minute rest periods. Resting-state activity was examined using regional homogeneity (ReHo), which estimates regional activation patterns through indices of localized concordance. ReHo values were compared between groups, followed by rs-FC analyses utilizing ReHo-localized areas as seeds to identify other involved regions. Relative to controls, ELS subjects demonstrated diminished ReHo in the inferior parietal lobule (IPL) and superior temporal gyrus (STG). ReHo values were inversely correlated with ELS severity. Secondary analyses revealed decreased rs-FC between the IPL and right precuneus/posterior cingulate, left fusiform gyrus, cerebellum and caudate in ELS subjects. These findings indicate that ELS is associated with altered resting-state activity and connectivity in brain regions involved in trauma-related psychiatric disorders. Future studies are needed to evaluate whether these associations represent potential imaging biomarkers of stress exposure.

Hours of work and rest in the rail industry

Currently, the National Transport Commission is considering four options to form the regulatory framework for rail safety within Australia with respect to fatigue. While the National Transport Commission currently recommends no limitations around hours of work or rest, we provide evidence which suggests regulatory frameworks should incorporate a traditional hours of service regulation over more flexible policies. Our review highlights: Shift durations >12 h are associated with a doubling of risk for accident and injury. Fatigue builds cumulatively with each successive shift where rest in between is inadequate (<12 h). A regulatory framework for fatigue management within the rail industry should prescribe limits on hours of work and rest, including maximum shift duration and successive number of shifts. Appropriately, validated biomathematical models and technologies may be used as a part of a fatigue management system, to augment the protection afforded by limits on hours of work and rest. A comprehensive sleep disorder screening and management programme should form an essential component of any regulatory framework.

Decreased interhemispheric resting-state functional connectivity in first-episode, drug-naive major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is shown to have structural and functional abnormalities in specific brain areas and connections by recent neuroimaging studies. However, little is known about the alterations of the interhemispheric resting-state functional connectivity (FC) in patients with MDD. In the present study, we used a newly developed voxel-mirrored homotopic connectivity (VMHC) method to investigate the interhemispheric FC of the whole brain in patients with MDD at rest.

METHODS

Twenty-four first-episode, drug-naive patients with MDD and 24 age-, gender-, and education-matched healthy subjects underwent a resting-state functional magnetic resonance imaging (fMRI). An automated VMHC approach was used to analyze the data.

RESULTS

Patients with MDD showed lower VMHC than healthy subjects in the medial prefrontal cortex (MPFC) and the posterior cingulate cortex/precuneus (PCC/PCu), two core regions within default mode network (DMN). Both left and right MPFC showed reduced FC with the other frontal areas and with right anterior cingulate gyrus (ACC), while PCC/PCu exhibited abnormal FC with the frontal areas and thalamus in patient group. Significant positive correlation was observed between VMHC in MPFC and persistent error response of Wisconsin Card Sorting Test (WCST-Pre) in patients. Further ROC analysis revealed that VMHC in the MPFC and PCC/PCu could be used to differentiate the patients from healthy subjects with relatively high sensitivity and specificity.

CONCLUSIONS

Our results suggest that decreased VMHC in brain regions within DMN may underlie the pathogenesis of MDD.

Exploring the opinions and perspectives of general practitioners towards the use of social networking sites for concussion management

INTRODUCTION

Social networking sites (SNSs) are increasingly being used for health-related purposes. Many patients now use sites such as Facebook to discuss symptoms, seek support, and search for advice on health conditions, including concussion. Innovative methods of delivering health information using these technologies are starting to emerge and it is important to seek the input of key stakeholder groups (including general practitioners) to establish their feasibility and to highlight areas of concern.

AIM

This study aimed to seek the opinions of general practitioners towards the use of SNSs in concussion management.

METHODS

Semi-structured interviews were captured with a digital voice recorder and analysed using interpretative description methodology. Participants were general practitioners whose caseload included persons with a concussion between the ages of 16 and 30 years, and who had treated a patient with a concussion in the past 12 months.

FINDINGS

The clinical experience of the participants ranged from 3 to 35 years and 50% of the participants had a Facebook account themselves. While all participants were positive towards the use of SNSs for this purpose, concerns were raised regarding the issues of privacy and moderation.

CONCLUSION

SNSs, particularly Facebook, have the potential (if correctly utilised) to be a viable adjunct to traditional concussion management programmes. In order for SNSs to be successfully used in this manner, the quality of information shared needs to be accurate and patients using them need to ensure that they get adequate cognitive rest.

Therapist perceptions and delivery of interoceptive exposure for panic disorder

Interoceptive exposure (IE) is widely regarded as an essential procedure in the cognitive-behavioral treatment of panic disorder (PD). However, treatment manuals differ substantially in their prescribed delivery of IE, and little research exists to inform the optimal manner of its implementation. The present study examined therapists' perceptions and delivery of IE for PD. Results revealed substantial variability in how clinicians provide IE. In contrast to the prolonged and intense manner in which exposure techniques are traditionally applied, many therapists reported delivering a low dose of IE accompanied by controlled breathing strategies. Concerns about the potential adverse effects of IE were common despite the fact that participants reported the actual occurrence of negative outcomes of IE in their own practice to be extremely infrequent. It is possible that some therapists deliver IE in a cautious manner in an attempt to minimize the perceived risks associated with this treatment.

Differences in cardiovascular and central nervous system responses to periods of mental work with a break

The purpose of the present study was to examine how an inserted break influences the cardiovascular and central nervous system responses during periods of mental work. Twelve males conducted two 20-min periods of mental work with a 3-min break between them. Cardiovascular and central nervous system responses were measured continuously. In comparison to the baseline, cardiovascular responses increased continuously even after the inserted break, while, on the contrary, central nervous system activity did not significantly increase during the work periods but relaxed during the break. The work performance increased during the second work period. These results suggest that the inserted break proposed by VDT guidelines in Japan was effective in relaxing the central nervous system but was insufficient to prevent the increase in cardiovascular load. The results also imply that taking rests frequently is important not only to maintaining performance but also to preventing cumulative physiological workloads.

Behavioral and psychophysiological responses to job demands and association with musculoskeletal symptoms in computer work

INTRODUCTION

The purpose of this study was to identify and compare individual behavioral and psychophysiological responses to workload demands and stressors associated with the reporting of musculoskeletal symptoms with computer work. Evidence is growing that the prevalence of musculoskeletal symptoms increases with longer hours of computer work and exposure to psychosocial stressors such as high workloads and unrealistic deadlines. Workstyle, or how an individual worker behaves in response to such work demands, may also be an important factor associated with musculoskeletal symptoms in computer operators.

METHOD

Approximately 8,000 employees of the Australian Public Service were invited to complete an on-line survey if they worked with a computer for 15 or more hours per week. The survey was a composite of three questionnaires: the ASSET to measure perceived organizational stressors, Nordic Musculoskeletal Questionnaire to measure reported prevalence of musculoskeletal symptoms and additional questions to measure individual work behaviors and responses.

RESULTS

934 completed surveys were accepted for analyses. Logistic regression was used to identify significant behavioral and work response predictors of musculoskeletal symptoms. Reporting of heightened muscle tension in response to workload pressure was more strongly associated, than other physical behavioral factors, with musculoskeletal symptoms for all body areas, particularly the neck (OR = 2.50, 95% CI: 2.09-2.99).

CONCLUSIONS

Individual workstyles in response to workload demands and stressors, including working with heightened muscle tension and mental fatigue, were significantly associated with musculoskeletal symptoms. Future risk management strategies should have a greater focus on the identification and management of those organizational factors that are likely to encourage and exacerbate adverse workstyles.

Functioning of the attentional networks at rest vs. during acute bouts of aerobic exercise

The present study explored the effects of three different activity conditions on three attentional functions: alerting, orienting, and executive control. A group of highly experienced cyclists performed the Attention Network Test-Interactions (Callejas, Lupiáñez, & Tudela, 2004) at rest, during moderate aerobic exercise, and during intense aerobic exercise. Results indicated that aerobic exercise accelerated reaction time and reduced the alerting effect compared with the rest condition. However, aerobic exercise did not modulate the functioning of either the orienting or the executive control attentional networks. No differences in reaction time or attentional functioning were observed between the two aerobic exercise workloads. The present results suggest that moderate aerobic exercise modulates the functioning of phasic alertness by increasing the general state of tonic vigilance.

The impacts of short break provision on families with a disabled child: an international literature review

There are widespread assumptions about the potential impacts of short breaks on family carers and disabled children. This review aims to evaluate the existing international research evidence concerning the impacts of short breaks on families with a disabled child. Electronic literature searches were conducted using ASSIA, PsycInfo, CINAHL, and Web of Science, and requests for information were sent to selected email lists. Of 60 articles or reports identified for inclusion in the review, the vast majority of studies were cross-sectional, with only eight studies using quasi-experimental pre-post designs or longitudinal designs. Nonetheless, the consistency with which some findings have been reported suggests that short breaks appear to have the potential to positively impact on not only the well-being of carers, but also the children receiving short breaks and their families as a whole. Additional research is warranted in a number of areas. First, research needs to consider the impact of short breaks on fathers. Second, there is a need to consider in more depth how short breaks can impact on the siblings of disabled children. Third, research could consider how best short breaks can be combined with other interventions to maximise the impact for disabled children and their families. Fourth, research needs to look at the longer term impact of short breaks on outcomes for disabled children and their families. What is needed is evidence on what type of short breaks are best for children and families with particular characteristics at particular times during the course of the child's maturation towards adulthood.

Impaired resting-state functional integrations within default mode network of generalized tonic-clonic seizures epilepsy

Generalized tonic-clonic seizures (GTCS) are characterized by unresponsiveness and convulsions, which cause complete loss of consciousness. Many recent studies have found that the ictal alterations in brain activity of the GTCS epilepsy patients are focally involved in some brain regions, including thalamus, upper brainstem, medial prefrontal cortex, posterior midbrain regions, and lateral parietal cortex. Notably, many of these affected brain regions are the same and overlap considerably with the components of the so-called default mode network (DMN). Here, we hypothesize that the brain activity of the DMN of the GTCS epilepsy patients are different from normal controls, even in the resting state. To test this hypothesis, we compared the DMN of the GTCS epilepsy patients and the controls using the resting state functional magnetic resonance imaging. Thirteen brain areas in the DMN were extracted, and a complete undirected weighted graph was used to model the DMN for each participant. When directly comparing the edges of the graph, we found significant decreased functional connectivities within the DMN of the GTCS epilepsy patients comparing to the controls. As for the nodes of the graph, we found that the degree of some brain areas within the DMN was significantly reduced in the GTCS epilepsy patients, including the anterior medial prefrontal cortex, the bilateral superior frontal cortex, and the posterior cingulate cortex. Then we investigated into possible mechanisms of how GTCS epilepsy could cause the reduction of the functional integrations of DMN. We suggested the damaged functional integrations of the DMN in the GTCS epilepsy patients even during the resting state, which could help to understand the neural correlations of the impaired consciousness of GTCS epilepsy patients.

Abnormalities in resting-state functional connectivity in early human immunodeficiency virus infection

Limited information is available concerning changes that occur in the brain early in human immunodeficiency virus (HIV) infection. This investigation evaluated resting-state functional connectivity, which is based on correlations of spontaneous blood oxygen level-dependent functional magnetic resonance imaging (fMRI) oscillations between brain regions, in 15 subjects within the first year of HIV infection and in 15 age-matched controls. Resting-state fMRI data for each session were concatenated in time across subjects to create a single 4D dataset and decomposed into 36 independent component analysis (ICA) using Multivariate Exploratory Linear Optimized Decomposition into Independent Components. ICA components were back-reconstructed for each subject's 4D data to estimate subject-specific spatial maps using the dual-regression technique. Comparison of spatial maps between HIV and controls revealed significant differences in the lateral occipital cortex (LOC) network. Reduced coactivation in left inferior parietal cortex within the LOC network was identified in the HIV subjects. Connectivity strength within this region correlated with performance on tasks involving visual-motor coordination (Grooved Pegboard and Rey Figure Copy) in the HIV group. The findings indicate prominent changes in resting-state functional connectivity of visual networks early in HIV infection. This network may sustain injury in association with the intense viremia and brain viral invasion before immune defenses can contain viral replication. Resting-state functional connectivity may have utility as a noninvasive neuroimaging biomarker for central nervous system impairment in early HIV infection.

Work demands and need for recovery from work in ageing seafarers

This study was conducted on a population of seafarers serving in the Royal Fleet Auxiliary (RFA), the organisation providing support at sea to the Royal Navy. An investigation into work-related fatigue in RFA personnel onboard ships was carried out following changes to the regulations concerning maximum retirement age, to determine whether age was associated with recovery from work demands. A total of 322 personnel aged from 19 to 61 years were interviewed onboard seven RFA ships. The Need for Recovery scale was used to measure fatigue and work demands exposure was measured using the Baecke questionnaire and the NASA Task Load Index. It was found that older personnel did not have higher work-related fatigue than younger personnel. A measure of frustration at work was found to be most strongly related to work-related fatigue, even in seafarers who carried out physically demanding jobs. Work-related fatigue was found to accumulate over time in personnel who continued to be exposed to work demands onboard a ship. Finally, a relatively high level of work-related fatigue was found in the RFA sample as a whole, which may hold implications for management interventions. It was concluded that older personnel in the RFA can cope with the day-to-day demands of working life as well as younger personnel, possibly due to a 'survivor effect', whereby those personnel who do not cope as well with work demands leave and find a different job, leaving only those who successfully deal with the demands of working life at sea. STATEMENT OF RELEVANCE: In order to manage work demands in seafarers, it is important to identify the most fatiguing demands. Age is of interest because of the demographic ageing of the workforce. Age was not associated with a higher need for recovery. Psychological work demands had a greater effect on need for recovery than physical work demands.

Modulation of thermal pain perception by stress and sweet taste in women with bulimia nervosa

OBJECTIVES

To investigate if the increased pain threshold in women with bulimia nervosa (BN) may be due to chronic stress-induced analgesia.

METHODS

We measured thermal pain threshold latency, blood pressure and heart rate in 21 women with BN and 21 healthy women (HW) under six consecutive conditions: rest I, mental arithmetic task, rest II, eating sweet food, rest III, cold-pressor test.

RESULTS

Thermal pain threshold latency was longer in BN than in HW in all six conditions. It increased during mental arithmetic test and remained increased during the rest of the experiment in both groups. In the BN group, the increase of pain threshold during mental arithmetic was positively correlated with illness duration. The differential modulation of pain threshold by stress in BN and HW could not be explained by autonomic system reactivity. In HW, the pain threshold increased more during eating and blood pressure increased more during mental stress; in BN, the pain threshold was highest in the mental stress condition and blood pressure was most increased during eating. During the cold pressor test, women with BN showed smaller blood pressure increase and tolerated the cold for shorter time than HW.

CONCLUSION

The observed marked modulation of pain threshold by experimental stress suggests that stress-induced analgesia is unlikely to account for baseline pain insensitivity in BN. Increased pain threshold in BN is a stable yet incompletely understood phenomenon, which may be related to the predisposition to or maintenance of the disorder.

Immediate effects of two relaxation techniques on healthy volunteers

This controlled study compared immediate effects of two relaxation techniques on state anxiety and sustained attention in healthy subjects. 86 volunteers (56 men and 30 women) were divided into two groups: the first 43 volunteers (age range 18 to 64) practiced 20 minutes of yoga-based Deep Relaxation Technique (DRT), while the second group of 43 volunteers (same age range), practiced 20 minutes Supine Rest (SR). State anxiety was assessed using the State Trait Anxiety Inventory (STAI A-State), and sustained attention was assessed using the Six Letter Cancellation (SLC) and Digit Letter Substitution (DLS) tests. All tests were administered immediately before, and immediately after, practice. A significant reduction in State Anxiety score (P < 0.001) was observed for the group practicing DRT, but not for the group practicing SR. For the sustained attention tests, however, there were significant increases in scores by both DRT and SR groups (P < 0.001). The results suggest that both interventions improve attention, but that only DRT reduces State Anxiety.

The resting brain and our self: self-relatedness modulates resting state neural activity in cortical midline structures

The resting brain shows high neural activity in various regions, the default-mode network, chief among them the cortical midline structures (CMS). The psychological correlate of high resting state neural activity in CMS remains however unclear though speculatively it has been associated with processing of internally-oriented self-relatedness. We used functional MRI to examine internally-oriented self-relatedness during the resting state period. This was indirectly done by letting subjects perceive emotional pictures followed by a fixation cross; the very same pictures were then rated subjectively according to their degree of self-relatedness in a postscanning session. This allowed us to correlate the picture ratings of self-relatedness with signal changes in the subsequent resting state period, i.e. fixation period. The emotional pictures' degree of self-relatedness parametrically modulated subsequent resting state signal changes in various CMS, including ventro- and dorsomedial prefrontal cortex and posterior cingulate cortex. This modulation could be distinguished from effects of emotion dimensions (e.g. valence, intensity) and evoked effects of self-relatedness during the stimulus period itself the latter being observed rather in subcortical regions, e.g. amygdala, ventral striatum, and tectum. In sum, our findings suggest that resting state neural activity in CMS is parametrically and specifically modulated by the preceding stimulus's degree of self-relatedness. This lends further support to the presumed involvement of these regions in processing internally-oriented self-relatedness as distinguished from externally-oriented self-relatedness.

Grooming, scratching and feeding: role of response competition in acute anorectic response to rimonabant in male rats

RATIONALE

Although the CB1 receptor antagonist/inverse agonist rimonabant acutely suppresses food intake in rodents, the behavioural specificity of this effect remains unclear.

OBJECTIVES

To profile the behavioural effects of rimonabant in a free-feeding context.

MATERIALS AND METHODS

Videoanalysis was employed to characterise the effects of acute rimonabant (1.5 and 3.0 mg/kg, IP) on the behaviour of non-deprived male rats exposed to palatable mash. Data were also collected on post-treatment weight gain, and, as prolonged appetite suppression has been found after single dosing with compounds of this series, rats were reassessed (drug-free) for food intake 7 days after initial testing.

RESULTS

Both doses of rimonabant not only decreased mash consumption (44-55%) but also reduced 24-h weight gain. Although videoanalysis confirmed the inhibitory effects of rimonabant on feeding behaviour, it also revealed concurrent reductions in locomotion, rearing and sniffing as well as substantial (up to tenfold) and dose-dependent increases in grooming and scratching. Timecourse analyses further revealed that rimonabant dose-dependently induced frequent episodes of atypical scratching that waned over the test but which were succeeded by prolonged and behaviourally disruptive grooming. Finally, as groups did not differ in mash consumption on retest, any prolonged anorectic effect of acute rimonabant dissipates within 7 days of treatment.

CONCLUSIONS

The anorectic response to rimonabant in male rats would appear to be due largely to response competition. This parsimonious conclusion is supported by the less profound (although still significant) increases in scratching and grooming observed in rats treated with a sub-anorectic dose (0.5 mg/kg) of the compound.

Differences between younger and older workers in the need for recovery after work

OBJECTIVE

The aim of this study was to test the hypothesis whether ageing workers have a higher need for recovery than younger workers.

METHODS

1100 subjects (84.3% participation rate) employed in the public sector participated in a cross-sectional questionnaire study. The subjects were divided into two age groups: older workers (> or =45 years) and younger workers (<45 years). The dependent outcome variable was assessed by "The Need for Recovery Scale" questionnaire. A need for recovery score higher than 45 was defined as a high need for recovery. A standardized questionnaire was used to assess psychosocial and physical work strain. Other occupational factors were included: part-time or full-time work, shift work and more than one employment. The following personal and social life and family related factors were also considered: gender, presence of chronic disease, degree of ability to cope with stress, number of children at home, taking care of disabled or elderly people, degree of satisfaction on family and social relationships. Stepwise multiple logistic regression analysis was used to examine the presence of a high need for recovery in older workers.

RESULTS

The mean recovery score was significantly higher in the group of the older workers (40.9) as compared to the younger workers (33.6) (P < 0.005). In the final multivariate logistic regression model the older age group had a significantly higher risk for the presence of a high need for recovery versus the younger group (OR 1.56, 95%CI 1.15-2.11). Gender, presence of musculoskeletal disorder, work pressure, monotonous work, social support from superiors, full time work and unsatisfactory social contacts were also significantly associated with the need for recovery.

CONCLUSION

The hypothesis that ageing workers have a higher need for recovery than younger workers was confirmed.

A short nap and natural bright light exposure improve positive mood status

While the effects of a short nap on performance and arousal level have been well investigated, less attention has been paid to its effects on mood status. The aim of the present study was to examine the effects of a short nap and natural bright light exposure on mood status. Participants were 16 healthy females who were on average 38.1 (SD = 2.68) yr old. From 11:00 to 12:00, the participants carried out a set of tasks twice with baseline lighting (<100 lux). From 12:40 to 13:10, they were subjected to three experimental conditions: control (<100 lux), natural bright light (>2,000 lux), and a 20-min nap. From 13:10 to 16:10, the tasks were repeated six times with the baseline lighting. To measure mood status, multiple visual analogue scales (to measure anxiety, sadness, anger, confusion, apathy, fatigue, and sleepiness) and the Mood Check List 3 (MCL-3) (to derive "pleasantness", "satisfaction" and "relaxation") were employed. The results showed that brief (30 min) natural bright light exposure improved one dimension of mood status, "pleasantness". A short nap also improved dimensions of mood status ("pleasantness", "satisfaction", and "relaxation"). These results suggest that the proper application of both natural light and a short nap shifts the mood status to the positive/favorable side.

Self-care requirements for activity and rest: an Orem nursing focus

According to Orem's self-care deficit nursing theory, helping people to maintain a balance between activity and rest (a universal self-care requisite) is a legitimate concern of nursing. The meaning of activity and rest, the requirements and potential measures for meeting this self-care requisite, and factors that might influence the process are explored. Criteria for determining a need for nursing, guides for a nursing clinical assessment, and guides for nursing action are suggested as potential ways to assist persons to meet the action demands associated with this self-care requisite.