Original article Contextual factors and perceived self-reported sleepiness: a preliminary report Amir Sharafkhaneh * , Max Hirshkowitz Sleep Disorders and Research Center, Veterans Affairs Medical Center and Baylor College of Medicine, Sleep Center 116A, 2002 Holcombe Boulevard, Houston, TX 77030, USA Received 9 October 2002; received in revised form 23 December 2002; accepted 24 December 2002 Abstract Objectives: The purpose of the present study was to determine whether contextual factors affect self-reported sleepiness. Specifically, when a reference situation is held constant (e.g. watching television), does the respondent’s position, location, or interest in the activity alter sleepiness rating. We also evaluated interactions between an individual’s level of sleepiness and the effect of these contextual factors. Method: This is a prospective survey conducted at a teaching hospital. Samples were drawn from four populations: a general non-patient population (n ¼ 53), a geriatric population (n ¼ 22), a medical resident population (n ¼ 18), and patients referred for sleep evaluation (n ¼ 53). We developed and administered a questionnaire that included a list of activities varied according to respondent’s position, location, or interest in the activity. This questionnaire, along with the Epworth Sleepiness Scale (ESS), was administered to 146 individuals. Results: Overall, we found significant differences (P , 0:01) in self-reported sleepiness when contextual factors were varied. However, the influence of contextual factors declined as a function of increasing sleepiness (estimated using ESS scores). Conclusions: The results of this preliminary study indicate that contextual factors can influence self-reported sleepiness rating; however, this influence diminishes as sleepiness increases. Thus, clarifying context may improve test sensitivity in more alert individuals but does not appear to add incremental value to self-reported sleepiness in sleepy patients. q 2003 Published by Elsevier B.V. Keywords: Self-reported sleepiness; Subjective sleepiness; Contextual parameters 1. Introduction Daytime sleepiness is a common, serious, and potentially life-threatening condition. Although both objective and subjective techniques exist for assessing sleepiness, clin- icians mainly rely on self-report. The most widely used sleepiness questionnaire is the Epworth Sleepiness Scale (ESS) [1]. ESS queries for self-rated probability of dozing in eight different situations. ESS is a global measure of self- reported sleepiness, is well validated [2], has been translated into several languages [3–5], and is extensively used in clinical setting and research [6,7]. Nonetheless, ESS correlation with objectively measured sleepiness (using Multiple Sleep Latency Test) and with pathophysiology underlying sleep-disordered breathing (apnea þ hypopnea index) is modest [8,9]. Factors postulated to unmask sleepiness include being sedentary, performing a non-stimulating task, and/or being in a comfortable environment. As noted by Dement and Carskadon [10], moment-to-moment variations in sleepi- ness are influenced by “such diverse stimuli as light, noise, room temperature, activity level, motivation, recumbency, anxiety, bladder fullness, hunger, thirst, excitement, atten- tion, and many others”. Thus, self-reported sleepiness should be influenced by the contextual factors, including the respondent’s position (standing, sitting, lying down), location (a public vs. private place), or an individual’s interest level in the activity (interesting vs. boring). Moreover, such factors may affect whether a person will inadvertently doze. In ESS, four of the eight situations explicitly probe sleepiness while an individual is seated, two others imply sitting, one specifies lying down, and in one question the individual’s position remains ambiguous (question 2: ‘Watching TV’). Respondent’s activity location and interest level are not otherwise considered in ESS. The purpose of this study was twofold. First, we wanted 1389-9457/03/$ - see front matter q 2003 Published by Elsevier B.V. doi:10.1016/S1389-9457(03)00002-9 Sleep Medicine 4 (2003) 327–331 www.elsevier.com/locate/sleep * Corresponding author. Tel.: þ 1-713-794-7318; fax: þ1-713-794-7558. E-mail address: amirs@bcm.tmc.edu (A. Sharafkhaneh).