Testing a single-case experimental design to study dynamic light exposure in people with dementia living at home

Most people with dementia live at home supported by informal caregivers, but disturbed sleep patterns may induce a heavy burden of care. The beneficial effects of bright light on their sleep, health, and well-being have been demonstrated in clinical settings, but not in a home situation. We evaluated a dynamic lighting system in a real-life longitudinal single-case experimental design (SCED) with people with dementia living at home. Eleven people with dementia and their informal caregivers were included in this study with four 4-week periods of alternating exposure and nonexposure in an introduction–withdrawal setup (ABAB). Objective light exposure data were collected and analyzed. The used study design seems applicable for this population and suitable for home use. Participant dropout did occur, but was due to health conditions rather than participant burden. The lighting system led to more light in the homes of the participants, as well as to higher actual individual light exposures, although the latter increased only moderately and not consistently across all participants, seasons, and times of day. The participants appreciated the lighting system even after 6 months. We reflect on individual differences, seasonal and daypart influences, and differential light effects. Recommendations and lessons learned are discussed

Personal control of correlated color temperature of light:Effects on thermal comfort, visual comfort, and cognitive performance

Recent studies have suggested that thermal and visual comfort are correlated, although the causality underlying this correlation is unclear. Personal control of correlated color temperature (CCT) provides individual visual comfort, but its effects on other parameters such as thermal comfort and cognitive performance remain underexamined. Therefore, we investigated if personal control of CCT can, on top of visual comfort, enhance thermal comfort and cognitive performance in office scenarios while exposed to mild cold (17 °C) using a 2x2 within-subject design. Sixteen participants were initially exposed to CCT of either 2700 K or 5700 K for 70 min. In the subsequent 70 min, participants either had free control of CCT or no control. As expected, personal control of CCT improved visual comfort and mitigated perceived eye-related symptoms. However, it did not significantly affect thermal comfort for either antecedent CCT. When the antecedent CCT was 5700 K, personal control of CCT increased alertness and physiological arousal, improved the planning and verbal cognitive performance, but, unexpectedly, decreased performance on mental spatial manipulation tasks. Additional analyses then explored the role of the psychological and personalization effects of personal control by controlling for the actual CCT. These suggest that control benefited visual comfort, eye-related symptoms, perceived task performance, pleasure, alertness and physiological arousal. This study is one of the first studies to demonstrate that visual comfort does not causally affect thermal comfort. Personal control of CCT benefits visual appraisals and eye-related symptoms, sometimes improves alertness, but differentially influences cognitive performance depending on the task type.</p

Match and Mismatch between Lived Experiences of Daytime Sleepiness and Diagnostic Instruments:A Qualitative Study amongst Patients with Sleep Disorders

Excessive daytime sleepiness is a common symptom of sleep disorders. Despite its prevalence, it remains difficult to define, detect, and address. The difficulties surrounding sleepiness have been linked to an ambiguous conceptualization, a large variety of scales and measures, and the overlap with other constructs, such as fatigue. The present study aims to investigate patients’ descriptions of sleepiness-related daytime complaints and their phenomenology. We performedsemi-directed interviews with patients diagnosed with obstructive sleep apnea (N = 15) or narcolepsy (N = 5). The interviewers took care of utilizing the participants’ terminology when describing daytime complaints related to their sleep disorder. Various aspects of the daytime complaints were investigated, such as their description and temporality. The transcribed content was thematicallyanalyzed using an eclectic coding system, yielding five themes. The participants used different interchangeable descriptors (tired, sleepy, fatigued, exhausted) to express their daytime complaints. They enriched their description with indexes of magnitude (ranging from ‘not especially’ to ‘most gigantic, extreme’), oppositions to other states (using antipodes like energy, alertness, wakefulness, orrest), and indications of fluctuations over the day. Interestingly, the participants often used metaphors to express their experiences and their struggles. The lived experiences of the patients were found to not always align with common self-reported monitoring tools of sleepiness and to relate only in part with current conceptions. In practice, it is important to probe daytime complaints, such as daytime sleepiness, with a broader consideration, for example, by exploring antipodes, consequences, and time-of-day fluctuations

Light, alertness, and alerting effects of white light:A literature overview

Light is known to elicit non-image-forming responses, such as effects on alertness. This has been reported especially during light exposure at night. Nighttime results might not be translatable to the day. This article aims to provide an overview of (1) neural mechanisms regulating alertness, (2) ways of measuring and quantifying alertness, and (3) the current literature specifically regarding effects of different intensities of white light on various measures and correlates of alertness during the daytime. In general, the present literature provides inconclusive results on alerting effects of the intensity of white light during daytime, particularly for objective measures and correlates of alertness. However, the various research paradigms employed in earlier studies differed substantially, and most studies tested only a limited set of lighting conditions. Therefore, the alerting potential of exposure to more intense white light should be investigated in a systematic, dose-dependent manner with multiple correlates of alertness and within one experimental paradigm over the course of day