Sleep, fatigue, and NK cell activity in healthy volunteers: significant relationships revealed by within subject analyses.

Poor sleep is thought to compromise health partially through its effect on immune function. Although experimental studies have shown that sleep deprivation reduces natural killer cell activity (NKCA) within individuals, cross-sectional studies of individuals in ordinary life have often failed to find such a relationship. The current study compared cross-sectional and longitudinal approaches to explore the association between sleep and NKCA. The relationship between NKCA and fatigue was also studied since individuals who are highly fatigued due to various clinical conditions often exhibit reduced NKCA. In the present study, fatigue and amount of sleep were assessed by self-report, and NKCA was assessed in peripheral blood samples collected from each of 45 healthy women at two time points approximately one month apart. Using cross-sectional analysis for each of the two sessions, sleep was related to NKCA only in the second session. Fatigue was not related to NKCA at either session. A within-subject design, however, revealed that an increase in the amount of sleep and decrease in levels of fatigue were related to an increase in NKCA. The current findings suggest that NKCA varies with amount of sleep or fatigue within an individual, and that this relationship may often be masked by large interpersonal differences in cross-sectional studies.

Acculturation and its relationship to smoking and breast self-examination frequency in African American women.

The concept of acculturation has been used to understand differences in health behaviors between and within a variety of racial and ethnic immigrant groups. Few studies, however, have examined the potential impact of acculturation on health behaviors among African Americans. The present study has two goals: 1) to reconfirm relations between acculturation and cigarette smoking; 2) to investigate the impact of acculturation on another type of health behavior, cancer screening and specifically breast self-examination (BSE). African American women (N = 66) attending an inner-city cancer-screening clinic completed study questionnaires. Results reconfirmed psychometric properties of the African American Acculturation Scale (AAAS); replicated the negative association between acculturation and lifetime smoking status; and found relations between acculturation and women's adherence to BSE frequency guidelines. Findings from this study raise the possibility that specific aspects of acculturation may better explain specific health behaviors.

Experiences of racist events are associated with negative health consequences for African American women.

This study investigated whether experiences of racist events were related to psychological distress, negative health behaviors, and health problems. Participants were 71 African American women (mean age 44.4) who were recruited from an urban cancer-screening clinic as part of a larger longitudinal study on familial risk of breast cancer. Participants completed three study assessments, approximately one month apart, and data were collected via self-report. Correlational analyses revealed that past year and lifetime racism were both related to psychological distress. Among smokers and drinkers, past year racism was positively correlated with number of cigarettes and drinks consumed. Lifetime racism was negatively related to perceived health, and positively related to lifetime history of physical disease and frequency of recent common colds. Analyses using a general linear model revealed that these relationships were largely unaccounted for by other variables. In addition, demographic variables such as income and education were not related to experiences of racism. The results suggest that racism can be detrimental to African American's well being and should be investigated in health disparities research.