Chronotype Differences in Suicidal Behavior and Impulsivity Among Suicide Attempters
ABSTRACT Morning- and evening-type individuals differ on a number of psychological and biological variables. There has been increasing interest in the relationship between chronotype and personality traits. The aim of this study was to investigate the relationship between impulsivity and chronotype in suicide attempters. Eighty-nine suicide attempters were included in the study, and systematic information on suicide attempts was recorded. The Morningness-Eveningness Questionnaire was applied to determine chronotype, and attempter impulsivity was measured by the total score of the Barratt Impulsiveness Scale. Significant differences between chronotype and impulsivity scores were found. Evening-type subjects reported significantly higher impulsivity scores than both neither- and morning-types. A significant association between chronotype and type of suicide attempt was detected. The largest proportion of violent suicide attempters were evening-type subjects. Violent suicide attempters also reported significantly higher impulsivity scores than nonviolent attempters. Previous studies have pointed out possible relations between eveningness and impulsivity. Current findings suggest that eveningness may be a risk factor for violent suicide attempts by increasing impulsivity.
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ABSTRACT: Several studies documented that lower scores on the Morningness-Eveningness Questionnaire (MEQ) are associated with a higher global seasonality of mood (GSS). As for the Modern Man artificial lighting predominantly extends evening activity and exposure to light, and as evening bright light phase is known to delay circadian rhythms, this chronic exposure could potentially lead to both lower Morningness as well as higher GSS. The aim of the study was to investigate if the MEQ-GSS relationship holds in the Old Order Amish of Lancaster County, PA, a population that does not use network electrical light. 489 Old Order Amish adults (47.6% women), with average (SD) age of 49.7 (14.2) years, completed both the Seasonal Pattern Assessment Questionnaire (SPAQ) for the assessment of GSS, and MEQ. Associations between GSS scores and MEQ scores were analyzed using linear models, accounting for age, gender and relatedness by including the relationship matrix in the model as a random effect. GSS was inversely associated with MEQ scores (p=0.006, adjusted). include a potential recall bias associated with self-report questionnaires and no actual light exposure measurements. We confirmed the previously reported inverse association between MEQ scores and lower seasonality of mood, for the first time in a population that does not use home network electrical lighting. This result suggests that the association is not a byproduct of exposure to network electric light, and calls for additional research to investigate mechanisms by which Morningness is negatively associated with seasonality. Published by Elsevier B.V.Journal of Affective Disorders 11/2014; 174C:209-214. DOI:10.1016/j.jad.2014.11.039
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ABSTRACT: Morningness–eveningness describes individual preferences for activity at specified times of the day. The present research aimed to test whether sun time entrains humans and whether this effect is observable in sleep–wake timing, in the timing of social rhythm and in morningness preference. Furthermore, we tested whether different reference points (activity expressed in standard time or in sun time, morningness preference scores) provide concordant results about differences in chronotype according to longitude. University students were tested in two locations (Warsaw, Poland; Heidelberg, Germany) positioned within the same time zone but differing according to longitude, thus daylight appeared earlier in the east (Warsaw) than in the west (Heidelberg). Sampling was scheduled to obtain similar photoperiods and other environmental factors in two locations. Measures consisted of times of day when various activities occurred (e.g. going to bed, waking up, going outdoors) in the seven days prior to data collection, morningness preference, and depressiveness. Varsovians and Heidelbergers did not differ in morningness preference and depressiveness, but Varsovians, compared to Heidelbergers, undertook a number of activities (e.g. wake up, get up, having breakfast, first contact with another person and going outdoors) at an earlier clock time (21–38 min earlier, depending on activity), did not differ in starting and finishing classes/work, and were later in eating lunch and dinner. However, all the activities of Varsovians (except for going outdoors) were positioned later according to sun time reference. Thus, residents from east as compared to those from the west had similar morningness preference, were more morning positioned in many aspects according to standard time, but were later according to sun time. Results indicated university students entrained to sun time to some extent, and morning activities more coupled to sun time.Time & Society 06/2014; 23(2):258-276. DOI:10.1177/0961463X14535911
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ABSTRACT: Circadian rhythm disturbances have been associated with bipolar disorder (BD) during both the mood episodes and the periods of remission. Circadian phase preferences for the evening have been reported for remitted patients, whereas the amplitude and stability of their rhythms have never been assessed using questionnaires. The primary aim of our study was the validation of a French version of the Circadian Type Inventory (CTI), whereas its secondary aim was the comparison between remitted patients with BD and healthy controls for rhythm stability and amplitude and for phase preference. For this purpose, we used the CTI and the Composite Scale of Morningness (CSM) that assesses phase preference (''morning'' or ''evening'' type). First, we report here on the validation of the French version of the 11-item Circadian Type Inventory in a sample of 140 remitted patients with BD and 156 healthy controls. Principal components analysis revealed a two-factor structure (FR: flexibility/rigidity scale corresponding to rhythm stability; LV: languid/vigorous scale corresponding to rhythm amplitude) explaining 52% of the variance in the control group and 47% in the bipolar group. Cronbach's alpha was 0.75 for FR and 0.73 for LV. The test-retest reliability was 0.74 for FR and 0.86 for LV (3 wks) and 0.62 for FR and 0.72 for LV (6 mos). LV and FR scores correlated with the Composite Scale of Morningness score (p50.00001 and p ¼ 0.0002, respectively). Second, as compared with controls, patients with BD were more languid (p50.00001) and showed an evening preference (p ¼ 0.0003), but they did not differ from the controls with regard to flexibility/rigidity. The French version of the CTI appeared to have satisfactory psy-chometrics characteristics. Bipolar patients exhibited not only abnormalities in phase preference but also in amplitude as measured by languidity. Since circadian rhythm dysfunction has been shown to predict poor functioning and mood relapses in interepisodic patients with BD, this tool would appear to be a promising, easy-to-use, measure of the amplitude and flexibility of circadian rhythms that could enrich the arsenal of assessments used in clinical settings.Chronobiology International 07/2013; DOI:10.3109/07420528.2013.798330