Seasonal Changes in Sleep Duration in African American and African College Students Living In Washington, D.C.

Duration of nocturnal melatonin secretion, a marker of “biological night” that relates to sleep duration, is longer in winter than in summer in patients with seasonal affective disorder (SAD), but not in healthy controls. In this study of African and African American college students, we hypothesized that students who met criteria for winter SAD or subsyndromal SAD (S-SAD) would report sleeping longer in winter than in summer. In addition, based on our previous observation that Africans report more “problems” with change in seasons than African Americans, we expected that the seasonal changes in sleep duration would be greater in African students than in African American students. Based on Seasonal Pattern Assessment Questionnaire (SPAQ) responses, African American and African college students in Washington, D.C. (N = 575) were grouped into a winter SAD/S-SAD group or a no winter diagnosis group, and winter and summer sleep length were determined. We conducted a 2 (season) × 2 (sex) × 2 (ethnicity) × 2 (winter diagnosis group) ANCOVA on reported sleep duration, controlling for age. Contrary to our hypothesis, we found that African and African American students with winter SAD/S-SAD report sleeping longer in the summer than in the winter. No differences in seasonality of sleep were found between African and African American students. Students with winter SAD or S-SAD may need to sacrifice sleep duration in the winter, when their academic functioning/efficiency may be impaired by syndromal or subsyndromal depression, in order to meet seasonally increased academic demands

Ubiquitination of human AP-endonuclease 1 (APE1) enhanced by T233E substitution and by CDK5

Apurinic/apyrimidinic endonuclease-1 (APE1) is a multifunctional DNA repair/gene regulatory protein in mammalian cells, and was recently reported to be phosphorylated at Thr233 by CDK5. We here report that ubiquitination of T233E APE1, a mimicry of phospho-T233 APE1, was markedly increased in multiple cell lines. Expression of CDK5 enhanced monoubiquitination of endogenous APE1. Polyubiquitinated APE1 was decreased when K48R ubiquitin was expressed, suggesting that polyubiquitination was mediated mainly through Lys48 of ubiquitin. The ubiquitination activity of MDM2, consistent in its role for APE1 ubiquitination, was increased for T233E APE1 compared to the wild-type APE1. In mouse embryonic fibroblasts lacking the MDM2 gene, ubiquitination of T233E APE1 was still observed probably because of the decreased degradation activity for monoubiquitinated APE1 and because of backup E3 ligases in the cells. Monoubiquitinated APE1 was present in the nucleus, and analyzing global gene expression profiles with or without induction of a ubiquitin-APE1 fusion gene suggested that monoubiquitination enhanced the gene suppression activity of APE1. These data reveal a delicate balance of ubiquitination and phosphorylation activities that alter the gene regulatory function of APE1

Age-Adjusted Means for Winter Sleep Duration and Summer Sleep Duration, by Sex, Ethnicity, and Winter Diagnosis Group Winter Sleep Summer Sleep

Duration of nocturnal melatonin secretion, a marker of "biological night" that relates to sleep duration, is longer in winter than in summer in patients with seasonal affective disorder (SAD), but not in healthy controls. In this study of African and African American college students, we hypothesized that students who met criteria for winter SAD or subsyndromal SAD (S-SAD) would report sleeping longer in winter than in summer. In addition, based on our previous observation that Africans report more "problems" with change in seasons than African Americans, we expected that the seasonal changes in sleep duration would be greater in African students than in African American students. Based on Seasonal Pattern Assessment Questionnaire (SPAQ) responses, African American and African college students in Washington, D.C. (N = 575) were grouped into a winter SAD/S-SAD group or a no winter diagnosis group, and winter and summer sleep length were determined. We conducted a 2 (season) × 2 (sex) × 2 (ethnicity) × 2 (winter diagnosis group) ANCOVA on reported sleep duration, controlling for age. Contrary to our hypothesis, we found that African and African American students with winter SAD/S-SAD report sleeping longer in the summer than in the winter. No differences in seasonality of sleep were found between African and African American students. Students with winter SAD or S-SAD may need to sacrifice sleep duration in the winter, when their academic functioning/efficiency may be impaired by syndromal or subsyndromal depression, in order to meet seasonally increased academic demands. KEYWORDS: seasonality, ethnicity, seasonal affective disorder, sleep duration, college students, biological night Volkov et al.: Seasonal Changes in Sleep Duration TheScientificWorldJOURNAL (2007) 7, 880-887 881 INTRODUCTION From a biological standpoint, sleep duration is determined by an interaction between the circadian pacemaker and the sleep homeostat The seasonality of sleep observed in mood-and sleep-disordered populations is also present in the general population, albeit to a lesser degree. In an epidemiological survey of Maryland residents, 92% of contacted individuals reported seasonal changes in sleep duration and 27% considered it a noticeable problem Sleep duration is related to the duration of the "biological night" as programmed by the circadian pacemaker and defined by neuroendocrine markers, such as the duration of nocturnal melatonin secretion Another factor associated with the degree of seasonal changes in sleep duration is geographic latitude. Results from a population study at four U.S. latitudes found that Florida residents reported less seasonality of sleep than Maryland, New York, or New Hampshire residents, and that Maryland residents reported less than New Hampshire residents College students, as in the population at large, may exhibit seasonality in their sleep duration. For example, college students in Maine demonstrated a general tendency to sleep longer during the winter months Sleep is problematic in college students. Of particular importance, college students often engage in poor sleep hygiene behaviors and demonstrate marked variability in their sleep schedules Volkov et al.: Seasonal Changes in Sleep Duration TheScientificWorldJOURNAL (2007) 7, 880-887 882 The purpose of the present study was to compare self-reported sleep duration during winter vs. summer in a large sample of African and African American college students in the Washington, D.C. metropolitan area. Based on the finding that biological night, which is related to sleep duration, is longer during winter than summer in patients with SAD, but not in healthy controls METHODS Participants Participants were African and African American undergraduate and graduate students at four academic institutions in the Washington, D.C. metropolitan area, including three colleges/universities and one nursing school. The protocol was approved by the Institutional Review Board of the D.C. Department of Mental Health. Students signed an informed consent after a full description of the study. Inclusion criteria were (1) identifying oneself as African or African American and (2) a minimum of 2 years residency in the greater Washington, D.C. area. Measures Sleep duration was reported on the Seasonal Pattern Assessment Questionnaire (SPAQ) In prior studies, the SPAQ has been used to estimate SAD and S-SAD prevalence and computes a global seasonality score (GSS) Demographic Information A brief questionnaire was used to assess demographic and other background information (age, gender, place of birth, length of stay in U.S., level of education) in a classroom setting at their respective institutions. African or African American ethnicity was defined as identifying oneself as an African or as an African American. Volkov et al.: Seasonal Changes in Sleep Duration TheScientificWorldJOURNAL (2007) 7, 880-887 883 Statistical Analyses Using a mixed 4-factor within-subjects design where season is the within-subjects factor and sex, ethnicity, and seasonality are between-subjects factors, we conducted a 2 (season: winter, summer) × 2 (sex: male, female) × 2 (ethnicity: African, African American) × 2 (winter seasonal pattern: winter SAD/S-SAD diagnosis, no winter diagnosis) ANCOVA on reported sleep duration, controlling for age. RESULTS Demographic Characteristics Of the original sample of 820 students recruited for the study, 216 were excluded due to missing data on one or more of the variables in the analysis (i.e., winter sleep length, summer sleep length, ethnicity, sex, or age). An additional 29 participants were excluded because of inaccurate reporting of sleep duration (26 reported sleep duration ≤ 3 h, three reported sleep duration ≥ 24 h per day). The final sample of participants used in these analyses included 575 students (437 African Americans and 138 Africans). The sample was predominantly female (62.8%), had a mean age of 29.52 years (SD = 9.03; range = 17-67), had spent an average of 19.81 years (SD = 12.41) in the U.S., and obtained a mean GSS on the SPAQ of 8.60 (SD = 5.28). Regarding winter diagnostic groups, 13.5% of students met SPAQ criteria for winter SAD or S-SAD. Prevalence estimates for SAD and S-SAD in this sample have been reported elsewhere Winter and Summer Sleep Length Age-adjusted means for winter sleep duration and summer sleep duration are presented in DISCUSSION To our knowledge, this is the first study of seasonal changes in sleep in a non-Caucasian sample in the U.S. (i.e., African American and African students) and the largest study to focus on seasonality in sleep duration in university and college students. Our results in students who did not meet criteria for SAD is consistent with prior studies in this geographic region that found a longer sleep duration in the winter than in the summer among both the general population and individuals with winter SAD Our study is consistent with recent efforts focused on sleep and wakefulness in adolescents and young adults 884 In young adults, sleeping fewer hours is associated with poorer health Certainly, national origin rather than ethnicity may have an important contribution on seasonality. For instance, in a study that evaluated the relationship between seasonality and "eveningness-morningness", students of Italian origin, but not those of Spanish origin, had higher incidences of S-SAD in evening types compared to morning types . Considering the well-established seasonality of indoor and outdoor aeroallergens, it is important to note that it has been shown that sleep, daytime functioning, and mood changes are affected by inflammatory mediators and congestion connected to allergic rhinitis Finding that the students who met SAD criteria sleep shorter in winter as compared to summer was unexpected, as SAD patients, but not normal controls, have been reported to have prolonged biological nights (i.e., melatonin secretion) in winter compared to summer Another possibility for the finding of shorter sleep duration in students with winter SAD/S-SAD is the ethnic composition of the sample. Our sample was comprised of African American and African students of both sexes, and our winter diagnosis group included both SAD and S-SAD. In contrast, in the study in which patients had a shorter duration of melatonin secretion than controls in summer compared to winter, the participants were predominantly Caucasian males with clinically diagnosed SAD The most significant limitation of this study was the use of a retrospective self-report measure of sleep duration. Self-reported sleep duration is not as accurate as more objective measures, such as polysomnographic recordings. A previous study found that when self-ratings were compared with objective measures, participants tended to overestimate sleep onset latency and underestimate their frequency of awakenings In summary, African and African American students with winter SAD or S-SAD reported significantly shorter sleep duration in winter than in summer. Considering that winter SAD is considered a condition with a preponderance of atypical symptoms of depression (with increased rather than decreased sleepiness), this is an unexpected finding that has implications for future research involving students and seasonality, and for the development of effective sleep hygiene strategies for students. It is possible that students with SAD/S-SAD reach an impasse between decreased motivation, energy, and concentration associated with winter depression and increased academic demands in winter (e.g., midterm and final examinations) that results in sacrificing sleep duration and increasing wake duration to help compensate for decreased academic efficiency. It is also possible that typical symptoms of depression in winter SAD are more abundant than we previously thought in African and African American students, a possibility that will have to be explored in its own right. A limited awareness of SAD may contribute to the underdiagnosis and undertreatment of SAD ACKNOWLEDGMENT