Noise as a sleep aid: A systematic review

Background Shift work is associated with sleep disorders, which impair alertness and increase risk of chronic physical and mental health disease. In health care workers, shift work and its associated sleep loss decrease provider wellness and can compromise patient care. Pharmacological sleep aids or substances such as alcohol are often used to improve sleep with variable effects on health and well-being. Objective We tested whether use of noise-masking earbuds can improve reported sleep quality, sleepiness, and stress level in health care shift workers, and increase alertness and reaction time post night shift. Methods Emergency medicine resident physicians were recruited for a prospective, single-subject design study. Entrance surveys on current sleep habits were completed. For 14 days, participants completed daily surveys reporting sleep aid use and self-rated perceived sleepiness, tension level, and last nights’ sleep quality using an 8-point Likert scale. After overnight shifts, 3-minute psychomotor vigilance tests (PVT) measuring reaction time were completed. At the end of 14 days, participants were provided noise-masking earbuds, which they used in addition to their baseline sleep regimens as they were needed for sleep for the remainder of the study period. Daily sleep surveys, post–overnight shift PVT, and earbud use data were collected for an additional 14 days. A linear mixed effects regression model was used to assess changes in the pre- and postintervention outcomes with participants serving as their own controls. Results In total, 36 residents were recruited, of whom 26 participants who completed daily sleep surveys and used earbuds at least once during the study period were included in the final analysis. The median number of days of earbud use was 5 (IQR 2-9) days of the available 14 days. On days when residents reported earbud use, previous nights’ sleep quality increased by 0.5 points (P<.001, 95% CI 0.23-0.80), daily sleepiness decreased by 0.6 points (P<.001, 95% CI –0.90 to –0.34), and total daily tension decreased by 0.6 points (P<.001, 95% CI –0.81 to –0.32). These effects were more pronounced in participants who reported worse-than-average preintervention sleep scores. Conclusions Nonpharmacological noise-masking interventions such as earbuds may improve daily sleepiness, tension, and perceived sleep quality in health care shift workers. Larger-scale studies are needed to determine this interventions’ effect on other populations of shift workers’ post–night shift alertness, users’ long-term physical and mental health, and patient outcomes.

Sensory disconnection from the environment is a hallmark of sleep and is crucial for sleep maintenance. It remains unclear, however, whether internally generated percepts – phantom percepts – may overcome such disconnection and, in turn, how sleep and its effect on sensory processing and brain plasticity may affect the function of the specific neural networks underlying such phenomena. A major hurdle in addressing this relationship is the methodological difficulty to study sensory phantoms, due to their subjective nature and lack of control over the parameters or neural activity underlying that percept. Here we explore the most prevalent phantom percept, subjective tinnitus – or tinnitus for short – as a model to investigate this. Tinnitus is the permanent perception of a sound with no identifiable corresponding acoustic source. This review offers a novel perspective on the functional interaction between brain activity across the sleep-wake cycle and tinnitus. We discuss characteristic features of brain activity during tinnitus in the awake and the sleeping brain, and explore its effect on sleep functions and homeostasis. We ask whether local changes in cortical activity in tinnitus may overcome sensory disconnection and prevent the occurrence of global restorative sleep and, in turn, how accumulating sleep pressure may temporarily alleviate the persistence of a phantom sound. Beyond an acute interaction between sleep and neural activity, we discuss how the effects of sleep on brain plasticity may contribute to aberrant neural circuit activity and promote tinnitus consolidation. Tinnitus represents a unique window into understanding the role of sleep in sensory processing and clarification of this relationship may offer novel insights into therapeutic interventions in tinnitus management.

Objectives Sleep problems in children on the autism spectrum may be affected by core diagnostic characteristics, including stereotypy (restricted and repetitive behaviors). Little is known about the nature of sleep-related stereotypy and its role within sleep disturbance. This study aimed to improve our understanding of the types of sleep-related stereotypy, its potential role within sleep difficulties, and how parents manage night-time stereotypy, in children on the autism spectrum. Methods This qualitative study used thematic analysis to analyze clinical assessment reports obtained from 21 parents of children on the autism spectrum referred for behavioral sleep intervention. Five themes, including the types of stereotypy, timing within sleep problems, stereotypy as sleep-interfering, stereotypy as sleep-conducive, and parent-responses, were identified. A clinical case study illustrates the potential role of vocal stereotypy within night wakings, through functional assessment and treatment of sleep problems in a child on the autism spectrum. Results Stereotypy included vocal and motor behaviors and repetitive manipulation of objects. Parents perceived stereotypy as both problematic and as beneficial to sleep, which may differentially affect behavioral treatment. Parent responses to stereotypy were varied and included co-sleeping. The case study highlights the complexity of the sleep and stereotypy relationship and the difficulty in treating automatically maintained behavior in the sleep context. Conclusion The function that stereotypy serves in relation to sleep disturbance is unclear and may differ across and within children. It is important we seek to better understand the specific ways that stereotypy may affect sleep, and vice versa, to improve clinical management of sleep problems in children on the autism spectrum.