Subsyndromal seasonal affective disorder in Antarctica

Effect of daily light exposure on sleep in polar regions: A meta-analysis

Although studies have shown that light affects sleep in polar populations, the sample size of most studies is small. This meta-analysis provides the first systematic review of the effects of summer glare, spring and fall moderate daylight, and artificial lighting on general sleep problems (sleep duration, efficiency, and delay). This analysis included 18 studies involving 986 participants. We calculated the random effect size via an evidence-based meta-analysis that analysed the effect of bright/auxiliary light on sleep and the effect of three different types of light on sleep compared with conventional light. There was no significant correlation between specific light types and sleep duration. Intense summer light has a negative effect on sleep time and efficiency. Moderate, natural light in spring and autumn effectively delayed sleep but could not improve sleep efficiency. For artificial fill light, neither blue light nor enhanced white light has been found to have a significant effect. In summary, summer light has a detrimental effect on sleep in polar populations, and moderate natural light may be superior to conventional light. However, specific strategies to improve sleep and artificial lighting in polar populations must be explored further.

Vagal predominance correlates with mood state changes of winter-over expeditioners during prolonged Antarctic residence

OBJECTIVE

Winter-over expeditioners in Antarctica are challenged by various environmental and psycho-social stress factors, which may induce psychophysiological changes. The autonomic nervous system (ANS) plays a crucial role in the adaptation process under stress. However, the relationship between ANS activity and the mood states of expeditioners remains largely unexplored. This study aims to uncover the pattern of ANS adjustment under extreme Antarctic environments and provide new insights into the correlations between ANS activity and mood state changes, which may provide scientific data for medical interventions.

METHODS

Fourteen expeditioners at Zhongshan Station participated in this study. The study was conducted during four representative periods: pre-Antarctica, Antarctica-1 (pre-winter), Antarctica-2 (winter), and Antarctica-3 (summer). The heart rate variability (HRV) of the expeditioners was continuously measured for 24 hours to evaluate ANS activity. Plasma levels of catecholamines were tested by ELISA. Mood states were assessed by the Profile of Mood States (POMS) scale.

RESULTS

HRV analysis showed a disturbance of ANS during winter and summer periods. For frequency domain parameters, very low frequency (VLF), low frequency (LF), high frequency (HF), and total power (TP) significantly increased during the second half of the mission. Especially, LF/HF ratio decreased during summer, indicating the predominance of vagal tone. Results of the time domain analysis showed increased heart rate variability during the austral winter and summer. Plasma epinephrine (E) significantly increased during residence in Antarctica. Compared with pre-Antarctica, the vigor, depression, and anger scores of the expeditioners decreased significantly during the austral summer. Notably, the depression score showed a moderate positive correlation with LF/HF, while weak negative correlations with other HRV indicators, including TP, VLF, and LF. Anger score showed a moderate positive correlation with LF/HF and weak negative correlations with the average normal-to-normal (NN) interval, and the root mean square of differences between adjacent RR intervals (RMSSD). Plasma E level weakly correlated with the average NN interval.

CONCLUSION

Prolonged residence in Antarctica increased the ANS activities and shifted the cardiac autonomic modulation towards vagal predominance. The alteration of HRV correlated with mood states and plasma epinephrine levels.

Living on the edge: How to prepare for it?

Introduction

Isolated, confined, and extreme (ICE) environments such as found at Antarctic, Arctic, and other remote research stations are considered space-analogs to study the long duration isolation aspects of operational space mission conditions.

Methods

We interviewed 24 sojourners that participated in different short/long duration missions in an Antarctic (Concordia, Halley VI, Rothera, Neumayer II) or non-Antarctic (e.g., MDRS, HI-SEAS) station or in polar treks, offering a unique insight based on first-hand information on the nature of demands by ICE-personnel at multiple levels of functioning. We conducted a qualitative thematic analysis to explore how sojourners were trained, prepared, how they experienced the ICE-impact in function of varieties in environment, provided trainings, station-culture, and type of mission.

Results

The ICE-environment shapes the impact of organizational, interpersonal, and individual working- and living systems, thus influencing the ICE-sojourners' functioning. Moreover, more specific training for operating in these settings would be beneficial. The identified pillars such as sensory deprivation, sleep, fatigue, group dynamics, displacement of negative emotions, gender-issues along with coping strategies such as positivity, salutogenic effects, job dedication and collectivistic thinking confirm previous literature. However, in this work, we applied a systemic perspective, assembling the multiple levels of functioning in ICE-environments.

Discussion

A systemic approach could serve as a guide to develop future preparatory ICE-training programs, including all the involved parties of the crew system (e.g., family, on-ground crew) with attention for the impact of organization- and station-related subcultures and the risk of unawareness about the impact of poor sleep, fatigue, and isolation on operational safety that may occur on location.

The role of circadian phase in sleep and performance during Antarctic winter expeditions

The Antarctic environment presents an extreme variation in the natural light-dark cycle which can cause variability in the alignment of the circadian pacemaker with the timing of sleep, causing sleep disruption, and impaired mood and performance. This study assessed the incidence of circadian misalignment and the consequences for sleep, cognition, and psychological health in 51 over-wintering Antarctic expeditioners (45.6 ± 11.9 years) who completed daily sleep diaries, and monthly performance tests and psychological health questionnaires for 6 months. Circadian phase was assessed via monthly 48-h urine collections to assess the 6-sulphatoxymelatonin (aMT6s) rhythm. Although the average individual sleep duration was 7.2 ± 0.8 h, there was substantial sleep deficiency with 41.4% of sleep episodes <7 h and 19.1% <6 h. Circadian phase was highly variable and 34/50 expeditioners had sleep episodes that occurred at an abnormal circadian phase (acrophase outside of the sleep episode), accounting for 18.8% (295/1565) of sleep episodes. Expeditioners slept significantly less when misaligned (6.1 ± 1.3 h), compared with when aligned (7.3 ± 1.0 h; p < .0001). Performance and mood were worse when awake closer to the aMT6s peak and with increased time awake (all p < .0005). This research highlights the high incidence of circadian misalignment in Antarctic over-wintering expeditioners. Similar incidence has been observed in long-duration space flight, reinforcing the fidelity of Antarctica as a space analog. Circadian misalignment has considerable safety implications, and potentially longer term health risks for other circadian-controlled physiological systems. This increased risk highlights the need for preventative interventions, such as proactively planned lighting solutions, to ensure circadian alignment during long-duration Antarctic and space missions.

Mood and Sleep Status and Mental Disorders During Prolonged Winter-Over Residence in Two Korean Antarctic Stations

Purpose

Antarctica is a region with extreme climate, characterized by extreme cold and photoperiod. No research has been conducted on the mental health of Korean Antarctic dispatchers. The aim of this study was to investigate the status of mental illness and changes in mood and sleep among Korean crew members staying for a long-term period in the Antarctic station.

Methods

From 2017 to 2020, crew members who were dispatched from South Korea to two Antarctic stations for a one-year period participated in this study. The crew were evaluated for mood and sleep status and mental illness through psychological tests and interviews by board-certified psychiatrists once before departure and twice during their stay in Antarctica. The incidence of mental illness was confirmed and changes in sleep and depression were analyzed.

Results

A total of 88 participants were included in the final analysis, and 7 of them (8.0%) were diagnosed with mental disorders such as insomnia in early winter. The total Beck Depression Inventory (BDI) score increased significantly in the early winter period, and the total Insomnia Severity Index (ISI) and Pittsburgh Sleep Quality Inventory (PSQI) scores increased in both early and late winter. The difference in changes in mood and sleep symptoms before, during, and after dispatch between the two stations was not significant.

Conclusion

This is the first study to investigate the mental illness and mood and sleep status of Korean crews dispatched to Antarctica. In early winter, there were significant increases in mental illness and depressive symptoms, and a worsening of sleep status.

Psychosocial issues in isolated and confined extreme environments

PALINKAS, L.A., and P. SUEDFELD. Psychosocial Issues in Isolated and Confined Extreme Environments. NEUROSCI BIOBEHAV REV (1) XXX-XXX, 2020. Psychosocial elements of behavior and performance will significantly impact the outcomes of long duration missions in space, ranging from individual and team decrements to positive benefits associated with successful adaptation. This paper reviews our current understanding of the individual, interpersonal and organizational issues related to living and working in isolated and confined extreme (ICE) environments. Individual issues include changes in emotions and cognitive performance; seasonal syndromes linked to changes in the physical environment; and positive effects of adapting to ICE environments. Interpersonal issues include processes of crew cohesion, tension and conflict; interpersonal relations and social support; the impact of group diversity and leadership styles on small group dynamics; and crew-mission control interactions. Organizational issues include the influence of organizational culture and mission duration on individual and group performance, crew autonomy, and managerial requirements for long duration missions. Improved screening and selection, leadership, coping and interpersonal skills training, and organizational change are key elements to optimizing adjustment to the environment and preventing decrements during and after long duration missions.

From the midnight sun to the longest night: Sleep in Antarctica

Sleep disturbances are the main health complaints from personnel deployed in Antarctica. The current paper presents a systematic review of research findings on sleep disturbances in Antarctica. The available sources were divided in three categories: results based on questionnaire surveys or sleep logs, studies using actigraphy, and data from polysomnography results. Other areas relevant to the issue were also examined. These included chronobiology, since the changes in photoperiod have been known to affect circadian rhythms, mood disturbances, exercise, sleep and hypoxia, countermeasure investigations in Antarctica, and other locations lacking a normal photoperiod. Based on the combination of our reviewed sources and data outside the field of sleep studies, or from other geographical locations, we defined hypotheses to be confirmed or infirmed, which allowed to summarize a research agenda. Despite the scarcity of sleep research on the Antarctic continent, the present review pinpointed some consistent changes in sleep during the Antarctic winter, the common denominators being a circadian phase delay, poor subjective sleep quality, an increased sleep fragmentation, as well as a decrease in slow wave sleep. Similar changes, albeit less pronounced, were observed during summer. Additional multidisciplinary research is needed to elucidate the mechanisms behind these changes in sleep architecture, and to investigate interventions to improve the sleep quality of the men and women deployed in the Antarctic.

Incidence of psychiatric disorders after extended residence in Antarctica

OBJECTIVES

The incidence of psychiatric disorders and depressive symptoms was examined in a cohort of American men and women who spent an austral winter at two different research stations in Antarctica to determine whether extended residence of nonindigenous inhabitants in a polar region is associated with psychiatric morbidity.

STUDY DESIGN

Debriefings interviews with 220 men and 93 women were conducted by 3 psychiatrists and 1 clinical psychologist at McMurdo Station and South Pole Station at the end of the austral winter between 1994 and 1997. Crewmembers were assigned a DSM-IV diagnosis if they satisfied diagnostic criteria. Debriefed crewmembers also completed the Structured Interview Guide for the Hamilton Depression Inventory-Seasonal Affective Disorders version (SIGH-SAD).

RESULTS

Thirty-nine (12.5%) crewmembers presented with symptoms that met the criteria for one or more DSM-IV disorders. After weighting the prevalence to account for the low participation rate of civilian personnel, the incidence of DSM-IV disorders was 5.2%. Mood disorders were the most common diagnoses, accounting for 30.2% of all diagnoses, followed by adjustment disorders (27.9%), sleep-related disorders (20.9%), personality disorders (11.6%), and substance-related disorders (9.3%). Depressive symptoms as measured by the SAD-SIGH were significantly associated with female gender, military occupation, station, year of expedition, and DSM-IV diagnosis.

CONCLUSION

Differences in the distribution of symptoms and diagnoses by demographic and expedition characteristics suggests that the social environment may be a more powerful determinant than the physical environment of psychiatric disorders in a polar region.

Different adaptations of Chinese winter-over expeditioners during prolonged Antarctic and sub-Antarctic residence

Prolonged residence in Antarctica is characterized by exposure to isolated, confined, and extreme (ICE) environment. Winter-over expeditioners at research stations often exhibit a complex of psychophysiological symptoms, which varied by stations and sociocultural backgrounds. To understand the different patterns of psychophysiological responses provoked by environmental stress, we conducted a longitudinal assessment of mood and endocrine function in two groups of Chinese expeditioners who were deployed to sub-Antarctic (Great Wall Station, 62°S, N = 12) and Antarctic (Zhongshan Station, 66°S, N = 16) from December 2003 to 2005. Measures of mood, thyroid function, the levels of plasma catecholamine, and circulating interleukins were obtained at departure from China, mid-winter (Antarctica), end of winter (Antarctica), and return to China, respectively. The Zhongshan Station crew experienced significant increases in fatigue, anger, tension, confusion, and decrease in free thyroxine (FT4), norepinephrine (NE), and epinephrine (E) during the winter, increase in thyrotropin (TSH) and total triiodothyronine (TT3) when returning, whereas their counterparts at Great Wall Station only experienced increased TT3 after deployment. Moreover, compared with the Great Wall Station crew, the Zhongshan Station crew exhibited greater increase in anger, greater decrease in FT4, total thyroxine (TT4), NE and E over the winter, and greater increase in TSH when returning. Chinese expeditioners who lived and worked at the Antarctic station and the sub-Antarctic station for over a year showed different change patterns in mood and endocrine hormones. Negative mood and endocrine dysfunction were positively associated with the severity of environment. The study is a supplement to scientific knowledge on psychophysiological variation under ICE environment, which has certain applied value for the development of preventive countermeasures or interventions.

Sleep Quality Changes during Overwintering at the German Antarctic Stations Neumayer II and III: The Gender Factor

Purpose

Antarctic residence holds many challenges to human physiology, like increased psycho-social tension and altered circadian rhythm, known to influence sleep. We assessed changes in sleep patterns during 13 months of overwintering at the German Stations Neumayer II and III from 2008 to 2014, with focus on gender, as many previous investigations were inconclusive regarding gender-based differences or had only included men.

Materials & Methods

Time in bed, sleep time, sleep efficiency, number of arousals, sleep latency, sleep onset, sleep offset, and physical activity level were determined twice per month during seven overwintering campaigns of n = 54 participants (37 male, 17 female) using actimetry. Data were analyzed using polynomial regression and analysis of covariance for change over time with the covariates gender, inhabited station, overwintering season and influence of physical activity and local sunshine radiation.

Results

We found overall longer times in bed (p = 0.004) and sleep time (p = 0.014) for women. The covariate gender had a significant influence on time in bed (p<0.001), sleep time (p<0.001), number of arousals (p = 0.04), sleep latency (p = 0.04), and sleep onset (p<0.001). Women separately (p = 0.02), but not men (p = 0.165), showed a linear increase in number of arousals. Physical activity decreased over overwintering time for men (p = 0.003), but not for women (p = 0.174). The decline in local sunshine radiation led to a 48 minutes longer time in bed (p<0.001), 3.8% lower sleep efficiency (p<0.001), a delay of 32 minutes in sleep onset (p<0.001), a delay of 54 minutes in sleep offset (p<0.001), and 11% less daily energy expenditure (p<0.001), for all participants in reaction to the Antarctic winter’s darkness-phase.

Conclusions

Overwinterings at the Stations Neumayer II and III are associated with significant changes in sleep patterns, with dependences from overwintering time and local sunshine radiation. Gender appears to be an influence, as women showed a declining sleep quality, despite that their physical activity remained unchanged, suggesting other causes such as a higher susceptibility to psycho-social stress and changes in environmental circadian rhythm during long-term isolation in Antarctica.

Chronic artificial blue-enriched white light is an effective countermeasure to delayed circadian phase and neurobehavioral decrements

Studies in Polar Base stations, where personnel have no access to sunlight during winter, have reported circadian misalignment, free-running of the sleep-wake rhythm, and sleep problems. Here we tested light as a countermeasure to circadian misalignment in personnel of the Concordia Polar Base station during the polar winter. We hypothesized that entrainment of the circadian pacemaker to a 24-h light-dark schedule would not occur in all crew members (n = 10) exposed to 100-300 lux of standard fluorescent white (SW) light during the daytime, and that chronic non-time restricted daytime exposure to melanopsin-optimized blue-enriched white (BE) light would establish an a stable circadian phase, in participants, together with increased cognitive performance and mood levels. The lighting schedule consisted of an alternation between SW lighting (2 weeks), followed by a BE lighting (2 weeks) for a total of 9 weeks. Rest-activity cycles assessed by actigraphy showed a stable rest-activity pattern under both SW and BE light. No difference was found between light conditions on the intra-daily stability, variability and amplitude of activity, as assessed by non-parametric circadian analysis. As hypothesized, a significant delay of about 30 minutes in the onset of melatonin secretion occurred with SW, but not with BE light. BE light significantly enhanced well being and alertness compared to SW light. We propose that the superior efficacy of blue-enriched white light versus standard white light involves melanopsin-based mechanisms in the activation of the non-visual functions studied, and that their responses do not dampen with time (over 9-weeks). This work could lead to practical applications of light exposure in working environment where background light intensity is chronically low to moderate (polar base stations, power plants, space missions, etc.), and may help design lighting strategies to maintain health, productivity, and personnel safety.

Psychological changes arising from an Antarctic stay: systematic overview

Long-term stays in extreme environments, such as Polar Regions, may cause significant changes in the health and well-being of individuals. A systematic overview aimed to map studies about the psychological effects on Antarctic expeditioners. The reviewed data were categorized and divided into two thematic axes: Negative Effects, resulting from harmful psychophysiological variations caused by exposure to the polar stressors, which may present seasonal symptom patterns, altering cognitive performance, mood and interpersonal relationships; and Positive Effects, such as salutogenic results arising from successful adaption to environmental adversities. Due to the great deal of evidence, it is suggested that protection factors should be promoted through preventive approaches, such as psychological training and support in order to reduce symptoms and generate satisfactory adaptation to Antarctica.

Vitamin D homeostasis, bone mineral metabolism, and seasonal affective disorder during 1 year of Antarctic residence

Low serum vitamin D and increased parathormone levels were found to be associated with depression and stress in a wintering expedition of 20 healthy male subjects over a period of 1 year in Antarctica. The continuous daylight during summer and the dark polar winter affect endogenous vitamin D production. Long-term effects on bone health need to be studied further.

PURPOSE

Vitamin D plays a significant role in calcium and bone mineral metabolism and also affects cardiovascular, psychological, and cognitive functions. The ultraviolet B radiation component of sunlight, which shows marked seasonal variation in Antarctica, influences the synthesis of vitamin D. Depression and mood disorders are associated with this extreme photoperiod. In this study, we attempted to gauge the alteration of vitamin D homeostasis in Antarctica and its effect on bone mineral metabolism and mood over a period of 1 year.

MATERIALS AND METHODS

Twenty male subjects who wintered over at India's Antarctic base Maitri (70°45'57″ S, 11°44'09″ E) from November 2010 to December 2011 were studied. Fasting serum samples were collected at baseline, 6 months, and 12 months for serum 25-hydroxyvitamin D, intact parathyroid hormone (PTH), total alkaline phosphatase (ALP), calcium, and phosphate. Beck Depression Inventory (BDI), Positive and Negative Affect Scale (PANAS X), and Perceived Stress Scale were used to measure depression, affect, and stress.

RESULTS

Mild vitamin D deficiency was present in two (10 %) subjects on arrival, which increased to seven (35 %) subjects during the polar winter at 6 months. The mean score on the BDI-II screen for depression was significantly higher during midwinter (4.8 ± 3.9) when compared with the baseline value (2.9 ± 2.1). Only 2/20 (10 %) of subjects met the criteria for minor depression. Higher PTH levels at 6 months correlated with a higher PANAS X score (p = 0.021). The mean values of calcium, inorganic phosphorus, and ALP were comparable during the course of the expedition.

CONCLUSION

Low light exposure during the dark polar winter, lower vitamin D, and increased intact PTH levels were found to be associated with depression during 1 year of Antarctic residence. The low dietary intake and decreased solar radiation exposure during the polar winter reduce serum vitamin D levels in otherwise healthy individuals, which suggests that supplementation may be necessary.

Female gender but not season of birth is associated with mood seasonality in a near-equatorial Brazilian city

OBJECTIVE: Studies conducted mainly in countries located in the Northern Hemisphere have shown that season of birth influences mood seasonality. Greater mood seasonality has been observed for individuals born during spring/summer months than those born during autumn/winter months. Expanding past research to the Southern Hemisphere, in this study we examine the influence of season of birth on mood seasonality in a sample of 1,247 healthy young Brazilians. METHOD: The Seasonal Pattern Assessment Questionnaire was used to compute a global seasonality score as a measure of mood seasonality in a cross-sectional study. RESULTS: Analysis of covariance was conducted to examine the effects of month of birth and gender on mood seasonality, with age entered as a covariate. A main effect of gender was observed, F (1, 1197) = 17.86, p < .01; partial Eta-squared = .02, with mood seasonality being higher for females (M = 8) than for males (M = 7). Contradicting previous findings, no significant main effect for month of birth was observed, F (1, 1197) = 0.65, p > .05. CONCLUSION: The unexpected finding is tentatively explained by differences in geographic location and weather fluctuations between the sampling location in Brazil and other countries where season of birth has been found to influence mood seasonality. Additional studies with larger samples from the Southern Hemisphere are necessary to shed additional light on the possible significant influence of season of birth on mood.

The impact of bright artificial white and 'blue-enriched' light on sleep and circadian phase during the polar winter

Delayed sleep phase (and sometimes free-run) is common in the Antarctic winter (no natural sunlight) and optimizing the artificial light conditions is desirable. This project evaluated sleep when using 17,000 K blue-enriched lamps compared with standard white lamps (5000 K) for personal and communal illumination. Base personnel, 10 males, five females, 32.5±8 years took part in the study. From 24 March to 21 September 2006 light exposure alternated between 4-5-week periods of standard white (5000 K) and blue-enriched lamps (17,000 K), with a 3-week control before and after extra light. Sleep and light exposure were assessed by actigraphy and sleep diaries. General health (RAND 36-item questionnaire) and circadian phase (urinary 6-sulphatoxymelatonin rhythm) were evaluated at the end of each light condition. Direct comparison (rmanova) of blue-enriched light with white light showed that sleep onset was earlier by 19 min (P=0.022), and sleep latency tended to be shorter by 4 min (P=0.065) with blue-enriched light. Analysing all light conditions, control, blue and white, again provided evidence for greater efficiency of blue-enriched light compared with white (P<0.05), but with the best sleep timing, duration, efficiency and quality in control natural light conditions. Circadian phase was earlier on average in midwinter blue compared with midwinter white light by 45 min (P<0.05). Light condition had no influence on general health. We conclude that the use of blue-enriched light had some beneficial effects, notably earlier sleep, compared with standard white light during the polar winter.

Seasonal vegetative and affective symptoms in the Finnish general population: testing the dual vulnerability and latitude effect hypotheses

BACKGROUND

Prior studies identified a seasonal pattern in symptoms of depression in clinical and population-based samples. The aims of our study were to estimate the prevalence rates of routine seasonal variations in mood and behavior and of current depressive symptoms in the Finnish general population over 30 years, and to find differences, if any, between the northern and southern regions of residence.

METHODS

5749 participants aged 30-97 (3156 women and 2593 men) were interviewed face to face and attended a health status examination. We included the modified Seasonal Pattern Assessment Questionnaire and the modified Beck Depression Inventory (BDI) for the analysis.

RESULTS

85% of the sample, representative of a general population, had seasonal variations in mood and behavior; 9% of the sample scored high on both scales, thus having the routine seasonal variations together with a current self-report of winter depression. Scoring high on the former scale yielded the odds ratio of 3.12 for scoring high on the BDI. Neither the global seasonality score nor the BDI sum score was associated with latitude. No significant differences in affective symptoms were found by the latitude. The seasonal variation in sleep duration (P<0.001) was more prevalent in the northern regions.

LIMITATIONS

The seasonal variations were assessed with a self-report only.

CONCLUSIONS

A seasonal pattern in mood and behaviors was detected in a general population. Implications of our findings include the assessment of the seasonal variations as a risk factor of depressive illness.

Sleep during the Antarctic winter: preliminary observations on changing the spectral composition of artificial light

Antarctic Base personnel live for 3 months in winter with no natural sunlight. This project compared sleep, by actigraphy, during periods of increased exposure to white light or blue enriched light in 2003. The primary aim was to help define the optimum spectral composition and intensity of artificial environmental light. Nine men and one woman (33 +/- 7 years, mean +/- SD), wore activity and light monitors continuously from 28.2 to 9.10, and kept sleep diaries. Extra light was provided by light boxes (standard white, 5300 K, or prototype blue enriched, 10,000 K, Philips Lighting), which were turned on in bedrooms and in communal/work areas approximately 08.00-18.00 hours. After a no-treatment control period, 28.2-20.3, sequential 4-5 week periods of first white, then blue light, were imposed with a further control period 19.9-9.10. A limited baseline study in 2002 (no interventions) similarly measured light and activity in seven men and one woman (30 +/- 7 years). Daily light exposure in winter (lux, mean +/- SD) was doubled in 2003 (maximum 1039 +/- 281, average 64 +/- 21), compared to 2002 (572 +/- 276 and 30 +/- 11), P < 0.05 and P < 0.01, with no differences between white and blue light. There were no major differences in sleep between light conditions in 2003. A delay in sleep timing was found in midwinter compared to control (2003, bedtime, P < 0.05, sleep start, P < 0.05, sleep end, P < 0.01) and sleep fragmentation increased (P < 0.05). Sleep efficiency was slightly higher during all blue light periods compared to all white periods (P < 0.05). The use of higher intensity light of suitable spectral composition is proposed.

Psychological effects of polar expeditions

Polar expeditions include treks and stays at summer camps or year-round research stations. People on such expeditions generally undergo psychological changes resulting from exposure to long periods of isolation and confinement, and the extreme physical environment. Symptoms include disturbed sleep, impaired cognitive ability, negative affect, and interpersonal tension and conflict. Seasonal occurrence of these symptoms suggests the existence of three overlapping syndromes: the winter-over syndrome, the polar T3 syndrome, and subsyndromal seasonal affective disorder. About 5% of people on expeditions meet DSM-IV or ICD criteria for psychiatric disorders. However, they also experience positive or so-called salutogenic outcomes resulting from successfully coping with stress and enhanced self-sufficiency, improved health, and personal growth. Prevention of pathogenic psychological outcomes is best accomplished by psychological and psychiatric screening procedures to select out unsuitable candidates, and by providing access to psychological support, including telephone counselling. Promotion of salutogenic experiences is best accomplished by screening for suitable personality traits, and training participants in individual coping strategies, group interaction, and team leadership.

Social support and depressed mood in isolated and confined environments

The influence of isolation and confinement on social support and depressed mood was examined in a study of 235 men and women who spent a year at McMurdo Station in Antarctica, and a study of 77 men and women who spent a year at the Amundson-Scott South Pole Station. Although availability of support remained unchanged, there was a significant decrease in reported satisfaction with support obtained, as well as a significant increase in depressed mood. Satisfaction with support was inversely associated with depressed mood at the beginning and end of isolation and confinement. At the end of winter, this association varied by source of support. High levels of tension-anxiety, depression and anger preceded an increase in advice seeking, but high levels of advice seeking also preceded an increase in tension-anxiety and depression. Results suggest a significant erosion of social support under conditions of prolonged isolation and confinement, leading to an increase in depressed mood.

The psychology of isolated and confined environments. Understanding human behavior in Antarctica

Psychosocial adaptation to isolated and confined environments exhibits 4 distinct characteristics. First, it is seasonal: Variations in mood are associated with the altered diurnal cycle and psychological segmentation of the mission. Second, it is situational: Concurrent measures of personality, interpersonal needs, and coping styles are better predictors of mood and performance than are predeployment measures. Third, it is social: Members of expeditions with low social coherence report significantly more depression, anxiety, and anger than individuals belonging to expeditions with high social coherence. Fourth, it is salutogenic: Depressed mood is inversely associated with the severity of the physical environment of the station, and the winter-over experience is associated with reduced subsequent rates of hospital admissions, suggesting positive benefits for individuals seeking challenging experiences.

A 1-year, three-couple expedition as a crew analog for a Mars mission

This study assessed the intrapersonal and interpersonal functioning of a three-couple expedition group that included a 2 1/2-year-old child which was ice-locked on a boat in the High Arctic during a major portion of the expedition. Personality assessment indicated that team members were generally well adjusted, scoring relatively higher on well-being and achievement and relatively lower on stress reactivity. Weekly mood ratings showed that the group exhibited significantly higher positive than negative affect. Reported negative events were relatively most frequent at the beginning of the Arctic stay and toward the end of the darkness period and were lowest during the initial darkness interval. The period of darkness had both a salutary and negative impact. A highly important means of coping with stress was seeking emotional support from one's partner. Selection of couples with strong bonds with their partner appears to be one viable approach for crew selection for long-duration missions.

A comparison of open treatment of seasonal major and minor depression with light therapy

BACKGROUND

Although several investigators have described a milder form of seasonal affective disorder (SAD), called subsyndromal SAD, little is known about the effect of light therapy in this group. The current study evaluates 3 weeks of open treatment with light therapy in SAD and subsyndromal SAD patients.

METHODS

Subjects with major or minor depression according to DSM-IV with a seasonal pattern were recruited during the winter of 1998-1999 from clinic patients and media advertising. Subjects were commenced on open treatment of morning light therapy, for 30 min daily using a new fluorescent light therapy unit that produced approximately 5,000 lux at a distance of 12 inches. The treatment lasted 3 weeks and at the end of the first and second week of treatment the duration of exposure could be increased to a maximum of 60 min at the discretion of the clinician. The Structured Interview Guide for the Hamilton Depression Rating Scale-SAD version (SIGH-SAD) was administered weekly to evaluate outcome. Response was defined in a variety of ways to reflect the fact that subsyndromal SAD subjects had milder symptoms.

RESULTS

Forty-six subjects entered treatment and 44 (SAD, n = 29, subsyndromal SAD, n = 15) completed at least 2 weeks. Response rates were generally similar in SAD subjects (64-69%) and subsyndromal SAD (40-67%) patients. There was a trend for longer exposure to be associated with better outcome.

CONCLUSIONS

Light therapy may be an effective treatment for subjects with both major and minor depression with a seasonal pattern. Optimal duration, for the light therapy unit used in this study, is likely 45-60 min daily.

Seasonal affective disorder in an Arctic community

OBJECTIVE

To determine the rate of seasonal-pattern depression in an Inuit community above 70 degrees N.

METHOD

One-hundred and eleven people from randomly selected households were surveyed for depression and anxiety and the effect of the seasons on their mood. Eighty-eight people provided replies on the influence of the seasons.

RESULTS

One in five (22.6%) of the community sample was found to be depressed. Of these, seven (6.3%) had seasonal affective disorder (SAD), with fall onset occurring in six of these (5.4%). Subsyndromal SAD (SSAD) occurred in 11.7%, while any effect of the seasons (seasonality) occurred in 39.6%. Persons with SSAD and seasonality were significantly older than those unaffected by the seasonal effect. No other significant correlation of SAD, SSAD, or seasonality occurred with gender, age, and language preference.

CONCLUSION

Seasonal mood changes in this Inuit group living in the Canadian Arctic are elevated above the rates found in other studies using similar survey methods.

Estimated prevalence of the seasonal subtype of major depression in a Canadian community sample

OBJECTIVE

To examine estimates of lifetime prevalence of seasonal affective disorder (SAD) in Toronto, Ontario.

METHOD

Random telephone numbers were generated for the city of Toronto, and 781 respondents completed a telephone interview. Trained nonphysician interviewers conducted all interviews, which involved structured questions for diagnosing major depression. Patterns of symptom change across seasons were evaluated to establish a diagnosis of SAD according to DSM-III-R criteria.

RESULTS

Correcting for sex and age, the prevalence of SAD defined by DSM-III-R criteria was 2.9% (95% CI, 1.7% to 4.0%), and the overall lifetime prevalence of major depression in the sample was 26.4% (95% CI, 23.3% to 29.4%). Some subjects were contacted for a follow-up interview conducted in person; the positive predictive value for the diagnosis of major depression for the telephone interview was 100%, and the negative predictive value was 93%.

CONCLUSIONS

The seasonal subtype of depression represents 11% of all subjects with major depression, suggesting that SAD is a significant public health concern. The telephone interview demonstrated adequate reliability, indicating that it is appropriate for epidemiological surveys of this nature.

Stages of change in mood and behavior during a winter in Antarctica

Seasonal variation in mood and behavior was examined in 87 American men and women who spent the 1991 austral winter at three different research stations in Antarctica. The South Pole station (90 degrees S) crew reported a significant decline in tension/anxiety, depression, anger, confusion, and fatigue from March to August, followed by a significant increase in tension/anxiety and fatigue and a significant decline in vigor from August to October. The McMurdo station (78 degrees 51' S) crew also reported a significant decline in tension/anxiety from March to July and a significant increase in tension/anxiety from July to August. In contrast, the Palmer station (64 degrees 46' S) crew experienced no significant changes in any mood subscale from May to October. The nonlinear pattern of change in mood suggests that adaptation to prolonged isolation and confinement in an extreme environment occurs in two or three stages.

Arctic cognition: a study of cognitive performance in summer and winter at 69 degrees N

Evidence has accumulated over the past 15 years that affect in humans is cyclical. In winter there is a tendency to depression, with remission in summer, and this effect is stronger at higher latitudes. In order to determine whether human cognition is similarly rhythmical, this study investigated the cognitive processes of 100 participants living at 69 degrees N. Participants were tested in summer and winter on a range of cognitive tasks, including verbal memory, attention and simple reaction time tasks. The seasonally counterbalanced design and the very northerly latitude of this study provide optimal conditions for detecting impaired cognitive performance in winter, and the conclusion is negative: of five tasks with seasonal effects, four had disadvantages in summer. Like the menstrual cycle, the circannual cycle appears to influence mood but not cognition.

Seasonal affective disorder and latitude: a review of the literature

BACKGROUND

The aim of the study is to investigate the relationship between the prevalence of SAD and latitude.

METHODS

An overview of the epidemiological literature on the prevalence of SAD is given and studies relevant for the latitudinal dependency of prevalence will be analyzed and discussed.

RESULTS

The mean prevalence of SAD is two times higher in North America compared to Europe. Over all prevalence studies, the correlation between prevalence and latitude was not significant. A significant positive correlation was found between prevalence and latitude in North America. For Europe there was a trend in the same direction.

CONCLUSIONS

The influence of latitude on prevalence seems to be small and other factors like climate, genetic vulnerability and social-cultural context can be expected to play a more important role. Additional controlled studies taking these factors into account are necessary to identify their influence.

Seasonal affective disorder: report from India (latitude 26 degrees 45'N)

BACKGROUND

A number of studies have established the entity of seasonal affective disorder (SAD) and delineated the presence of atypical depressive features of carbohydrate craving, hyperphagia and hypersomnia. Most literature has emanated from research carried out in temperate climates, and only few reports are available from tropical countries, especially India.

METHODS

Consecutive patients with recurrent mood disorder (who had at least 2 episodes of depression in the past) comprised the study sample. The diagnosis of mood disorder was made according to DSM-III-R criteria. The sample was divided into two groups - seasonal and non-seasonal according to the DSM-III-R criteria of seasonal pattern. The depressed patients were rated on SADD and HDRS, and manic patients on BRMRS.

RESULTS

Eighteen of 93 patients fulfilled the criteria of seasonal pattern; 7 of these seasonal patients, and 25 of the non-seasonal patients were currently in depressive phase. Males dominated the sample in both the groups. The seasonal and non-seasonal groups as regards symptomatology, differed only on a few items - decreased libido on SADD, and suicidal ideation and helplessness on HDRS. Atypical vegetative features were not seen in any of the seasonal patients.

CONCLUSIONS

SAD is seen at lower latitudes also, although atypical vegetative features are not a prominent part of the symptomatology.

LIMITATIONS

The study sampled was obtained from a very select population, and thus does not indicate the prevalence of SAD in India. Secondly, the small sample size precludes any categorical comments of the symptomatology. Moreover, winter and summer depressives were considered as one group.

CLINICAL RELEVANCE

Emphasising the presence of SAD in a tropical country where there is relatively less variation in daylight periods, this report forms a base for future studies. It also raises the question of the role of variations in daylight in the aetiology SAD.