Measuring Sleep Efficiency: What Should the Denominator Be?

ABSTRACT: Inconsistency in operationally defining sleep efficiency (SE) creates confusion with regard to the conceptualization and use of the construct by researchers and clinicians. The source of the inconsistency is the denominator of the widely published operational definition of SE: ratio of total sleep time (TST) to time in bed (TIB) (multiplied by 100 to yield a percentage). When taken literally, TIB includes non-sleep-related activity (e.g., reading, texting, conversing with a partner, watching television) both prior to initiating sleep and after the final awakening. However, the construct of SE refers to TST compared to the amount of time spent attempting to initially fall asleep and sleep discontinuity. Non-sleep related activities in bed do not reflect that construct. Also, time out of bed during nighttime awakenings, a manifestation of sleep discontinuity, should be included in the SE denominator. Using TIB as the denominator can also create a methodological problem when SE is an outcome measure in sleep intervention research. It is proposed that research and practice would benefit by clarifying and adopting a consistent operational definition that more accurately captures the construct of SE. An alternate denominator, duration of the sleep episode (DSE), is suggested, where DSE = sleep onset latency (SOL) + TST + time awake after initial sleep onset but before the final awakening (WASO) + time attempting to sleep after final awakening (TASAFA). The proposed formula for SE would be: SE = TST / DSE (× 100). DSE can be easily calculated using standard sleep diary entries along with one item from the Expanded Consensus Sleep Diary. Implications for insomnia research and practice are discussed.

Pain and functional impairment as mediators of the link between medical symptoms and depression in type 2 diabetes.

BACKGROUND: Among people with diabetes, depression is more common and is associated with greater morbidity and mortality. A better understanding of mechanisms underlying the link between poor health and depression is needed. Pain and functional impairment may account for the effect of poor health on depression in diabetes. PURPOSE: The purpose of the study was to examine whether pain and functional impairment mediate the association between diabetes-related medical symptoms and depression in type 2 diabetes. METHOD: Adults diagnosed with type 2 diabetes (N = 77) completed the following measures: Patient Health Questionnaire (PHQ), Diabetes Symptom Checklist (DSC), and Medical Outcomes Study 12-item Short-Form Health Survey (SF-12). Body mass index (BMI) was computed using height and weight data from medical records. Mediation and linear regression analyses were conducted. RESULTS: Pain and functional impairment made significant, independent contributions to depression. Functional impairment mediated the link between diabetes-related medical symptoms and depression. Pain mediated the association between higher BMI and depression. CONCLUSION: Pain and functional impairment appear to play important, independent roles in depression in type 2 diabetes. Mediation analyses suggest the following: 1. diabetes-related medical problems increase functional impairment, which in turn leads to greater depression; and 2. the burden of carrying greater body mass (higher BMI) increases pain, which leads to increased depression.

Educational attainment moderates the effect of a brief diabetes self-care intervention.

AIMS: Those with less education are at increased risk for developing diabetes and have a poorer prognosis. Intensive diabetes self-care interventions have been more effective at improving glycemic control in those with lower educational attainment. Due to limited resources, the focus has shifted to brief, cost-effective health interventions. This study examined whether educational attainment moderates the effect of a brief, telephone delivered self-care intervention on glycemic control in people with type 2 diabetes. METHODS: Randomized clinical trial. Participants (N=62) were assigned to receive treatment as usual or treatment as usual plus a brief telephone intervention. The primary outcome measure was hemoglobin A1c. RESULTS: A significant education by intervention group interaction effect indicated that participants with higher educational attainment had greater improvement in glycemic control (A1c) than those with less educational attainment; whereas, educational attainment was unrelated to change in glycemic control (A1c) within the control group. CONCLUSIONS: People with higher educational attainment may benefit to a greater extent from brief self-care interventions for diabetes, while those with lower educational attainment may require more intensive treatment.

Depression and hemoglobin A1c in type 1 and type 2 diabetes: the role of self-efficacy.

AIMS: To examine a self-efficacy explanation of the finding that depression is related to hemoglobin A1c (A1c) level in people with type 1 but not type 2 diabetes. METHODS: Cross-sectional design involving 124 participants with type 1 (n=32) and type 2 (n=92) diabetes. Participants completed measures of depression and diabetes-related self-efficacy. A1c was obtained from medical records. RESULTS: Replicating prior findings, A1c was significantly correlated with depression in type 1 participants (r=.51, p<.01), but not in type 2 participants (r=.11, ns). As hypothesized, A1c was significantly correlated with self-efficacy among type 1 participants (r=-.42, p<.05) but not among type 2 participants (r=-.01, ns). Self-efficacy also mediated the effect of A1c on depression among the type 1 participants (Z=2.21, p<.05). CONCLUSION: In people with type 1, but not type 2 diabetes, A1c levels are related to diabetes adherence mastery (self-efficacy), which mediates the link between A1c and depression. Results are discussed with regard to the proposal that perceptions of ineffective control over one's health play a role in the development of depression (a consequence model of depression in diabetes).

Effect of a brief, regular telephone intervention by paraprofessionals for type 2 diabetes.

Brief, cost-effective interventions to promote diabetes self-management are needed. This study evaluated the effects of a brief, regular, proactive, telephone "coaching" intervention delivered by paraprofessionals on diabetes adherence, glycemic control, diabetes-related medical symptoms, and depressive symptoms. Therapeutic mechanisms underlying the intervention's effect on the primary outcomes were also examined. Adults diagnosed with type 2 diabetes (N = 62) were randomly assigned to receive the "coaching" intervention and treatment as usual, or only treatment as usual. The intervention increased frequency of exercise and feet inspection, improved diet, reduced diabetes medical symptoms, and lowered depressive symptoms. Self-efficacy, reinforcement, and awareness of self-care goals mediated the treatment effect on depression, exercise, and feet inspection, respectively. A brief telephone intervention delivered by paraprofessionals had positive effects on type 2 diabetes patients.

Reliability of diabetes-specific social support scales.

The Diabetes Care Profile (DCP) is frequently used to assess diabetes-related quality of life. The social support scales have demonstrated internal consistency but test-retest reliability has not been established. Sixty-three type 2 diabetes patients participated in a telephone coaching study designed to improve diabetes control. The DCP was filled out at pre- and post-test. The test-retest reliabilities of three social support scales (Global, GET, GET-WANT) were calculated. At a mean retest interval of 6.5 months, the support scales showed reliabilities of 0.48 (Global and GET), and 0.38 (GET-WANT). The social support scales of the DCP show adequate long-term test-retest reliability.

Racial/ethnic differences in Body Mass Index: the roles of beliefs about thinness and dietary restriction.

The greater BMI of African American relative to Caucasian women is implicated in racial/ethnic disparities in health outcomes. The principal aim of the current study was to evaluate a theoretical account of racial/ethnic differences in BMI. Thin-ideal internalization, the perceived romantic appeal of thinness, dietary restriction, weight, and height were assessed via self-report measures on a sample of female undergraduates of African American (n=140) and Caucasian (n=676) race/ethnicity. Using structural equation modeling, support was obtained for the primary hypothesis that racial/ethnic differences in BMI are explained by Caucasian women's greater thin-ideal internalization and perceived romantic appeal of thinness, thereby resulting in greater levels of dietary restriction. Current findings illustrate the potential for racial/ethnic differences in sociocultural standards of appearance to influence racial/ethnic disparities in physical health, of which BMI is a marker, via effects on weight control behavior.

Adherence, body mass index, and depression in adults with type 2 diabetes: the mediational role of diabetes symptoms and self-efficacy.

OBJECTIVE: Evidence indicates that depression is linked to the development and worsening of diabetes, but the mechanisms underlying this link are not well understood. The authors examined the hypothesis that diabetes-related symptoms mediate the effect of both behavioral adherence and body mass index (BMI) on depression. In addition, they examined whether a prior finding that self-efficacy mediates the effect of behavioral adherence and BMI on depression would replicate with a larger sample size (W. P. Sacco, K. J. Wells, C. A. Vaughan, A. Friedman, S. Perez, & R. Morales, 2005). Also, the relative contributions of diabetes-related symptoms and self-efficacy to depression were evaluated. DESIGN AND PARTICIPANTS: Cross-sectional design involving adults diagnosed with Type 2 diabetes (N = 99). MAIN OUTCOME MEASURES: The primary outcome measure was depression (Patient Health Questionnaire: Nine Symptom Depression Checklist). Predictors of depression were diet and exercise adherence (Summary of Diabetes Self-Care Activities Questionnaire), diet and exercise self-efficacy (Multidimensional Diabetes Questionnaire), diabetes symptoms (Diabetes Symptom Checklist), and BMI (based on height and weight data from medical records). RESULTS: Path and mediation analyses indicated that adherence and BMI each contributed to depression indirectly, via their effects on self-efficacy and diabetes-related medical symptoms. CONCLUSION: Results provide evidence consistent with two independent pathways by which BMI and adherence could increase depression in people with Type 2 diabetes. The first pathway indicates that the effects of higher BMI and poor adherence on depression are mediated by lower self-efficacy perceptions. The second pathway indicates that the effect of higher BMI on depression is mediated by increased diabetes symptoms.

Diabetes and depression: the role of social support and medical symptoms.

Depression in people with diabetes is linked to poor physical health. Social support and physical health have been linked to each other and to depression. The present study examined three possible models of the interrelationship among depression, social support, and diabetes-related medical symptoms. Eighty-six diabetes patients completed measures of diabetes symptoms, depression, and diabetes-related social support. Depression, social support, and diabetes-related medical symptoms were significantly related to each other. Mediation analysis indicated that the effect of social support on diabetes-related medical symptoms was fully accounted for by social support's adverse effect on depression. Consistent with theory and research on interpersonal aspects of depression, a bi-directional relationship between depression and social support was suggested. That is, while both diabetes-related medical symptoms and social support independently contributed to depression, depression also contributed to lower social support. Findings underscore the potential importance of interpersonal factors in the physical health of individuals with diabetes.

Interpersonal factors predict increased desire for hastened death in late-stage cancer patients.

BACKGROUND: Cancer patients at the end of life sometimes express a wish that death would come quickly, but this desire for hastened death (DHD) remains little understood. Relationships with spousal caregivers may play a role in patients' DHD. PURPOSE: This study examined factors that could predict an increase in the DHD in late-stage cancer patients over the course of 4 months, including marital and caregiving variables that have not previously been examined. METHOD: Patients completed the Schedule of Attitudes Toward Hastened Death and other measures, including the Dyadic Adjustment Scale. Caregivers were asked how many hours they spent weekly in caregiving activities and completed the Caregiver Demands Scale. Approximately 4 months later, DHD was reassessed in surviving patients. RESULTS: Sixty caregiver/patient dyads completed all measures. Desire for hastened death was generally low at both assessments; however, more depression and greater dyadic adjustment reported by patients, and more hours spent in caregiving activities by spouses, each independently predicted increased DHD in patients at the Time 2 assessment. CONCLUSIONS: Findings suggest that issues related to spousal caregivers play an important role in the course of DHD in cancer patients at the end of life.

Depression in adults with type 2 diabetes: the role of adherence, body mass index, and self-efficacy.

Considerable evidence links depression with the development and worsening of diabetes, but the factors contributing to this link have not been established. The authors examined the role of adherence, body mass index (BMI), and self-efficacy. Adult patients with Type 2 diabetes (N = 56) completed self-report measures of diet and exercise adherence, diet and exercise self-efficacy, and depression. BMI was obtained from medical records. Path and mediation analyses indicated that both adherence and BMI independently contributed to self-efficacy. Self-efficacy mediated both the association between adherence and depression and the association between BMI and depression. These findings are consistent with the proposal that lower self-efficacy in reaction to adherence failure and higher BMI contributes to depression in adults with diabetes.

A brief, regular, proactive telephone "coaching" intervention for diabetes: rationale, description, and preliminary results.

Telephone-delivered interventions (TDIs) represent a potentially cost-effective method to increase medical adherence. TDIs for diabetes patients have typically been delivered by nurses or computerized telephone messaging. Psychology undergraduates, however, are less costly than nurses, have a strong background in behavioral science, and provide the personal relationship missing with computerized contact. This paper presents the rationale for and description of a brief, regular, proactive telephone intervention designed to be delivered by psychology undergraduates (i.e., paraprofessionals). "Coaches" administer a 15-min telephone intervention weekly for 3 months and biweekly for 3 additional months. Guided by a semistructured protocol that focuses on behavioral goals, coaches provides support, collaborative problem-solving, and apply basic cognitive-behavioral techniques. Results from a pilot study on type 1 diabetes patients are presented. This preliminary evidence suggests that the program is feasible, acceptable to a large majority of patients, and effective in reducing HbA1c levels.