Continuous white noise exposure during sleep and childhood development: A scoping review

White noise is defined as noise containing many frequencies of equal intensity. Devices capable of generating white noise are increasingly available as stand-alone machines or through mobile device applications (apps). They are commonly used to mask disturbing environmental noise to aid sleep initiation or maintenance in children. Growing concern, however, has surfaced surrounding potential deleterious developmental effects from chronic noise exposure during sleep. To this end, prior research has demonstrated that a substantial number of commercially available white noise generators are capable of generating low (<70 dB [dB]), moderate (70–80 dB), and high (>80 dB) intensity, even exceeding the 85 dB National Institute for Occupational Safety and Health (NIOSH) noise exposure threshold recommendations for an 8-h exposure [1]. Apps are potentially the most dangerous as these are governed by the maximum output of the cellular phone hardware, which can reach levels around 100 dB. These standards are set for adults but are used here as a surrogate marker for dangerous noise levels for children and infants as there are no comparable scales dedicated to this age group. Moreover, as these devices are commonly used in younger children who have extended sleep duration (i.e., 10+ hours), the potential negative developmental effect of long-term noise exposure may be magnified.

Existing publications surrounding the impact of chronic nighttime noise exposure on early cognitive and behavioral development in animals and humans span numerous journals across diverse specialties. Furthermore, given pragmatic challenges surrounding human investigation of chronic noise exposure during sleep, relevant studies are exclusively observational, oftentimes with variable study designs.

For these reasons, we present this scoping review to collate all relevant published literature on chronic nighttime noise exposure and early animal and childhood development. Our primary aims are assessing the current state of available evidence, identifying gaps where future research is required, and examining device use recommendations based on current evidence.

Methods

This scoping review was performed and reported in accordance with the 2018 Preferred Reporting Items extension for Scoping Reviews (PRISMA-ScR) guidelines [2]. An experienced medical librarian (C.J.C.) assisted in database searching and data extraction.

Embase, Ovid MEDLINE, the Cochrane Central Register of Controlled Trials, Scopus, and Web of Science were searched from database inception through June 2022. Articles were included if they were published in Chinese, English, German, Italian, or

Scoping review overview

The database search yielded 940 papers. After removal of 296 duplicates, 644 unique articles were retrieved. Among 50 articles published on potentially relevant material, 30 did not meet inclusion criteria; 15 were review articles, 12 were studies with disparate methodologies or study endpoints, and two articles could not be accessed beyond their abstract. The remaining 20 manuscripts were included for data extraction. This process is represented in Fig. 1. All were primary research articles.

Overview

This scoping review searched five databases from inception through June 2022 with limited language restrictions with the primary aim of gathering current evidence surrounding the effect of chronic nighttime noise exposure on childhood development to guide further research and current practice. Given the breadth and diversity of published literature on the topic, a comprehensive search strategy was developed with the help of an experienced medical librarian. This review underscores the

Conclusions

White noise machines can exceed 91 dB on maximum volume, which exceeds NIOSH safety guidelines for a 2-h shift. Evidence suggests deleterious effects of continuous moderate-intensity white noise exposure on early development in animal models. Human subject data generally corroborates these models; however, studies also suggest low-intensity noise exposure may be beneficial during sleep. Further research into the optimal intensity and duration of white noise exposure in children is needed.

CRediT authorship contribution statement

Russell W. De Jong: Writing – review & editing, Writing – original draft, Visualization, Investigation, Formal analysis, Data curation, Conceptualization. Gavin S. Davis: Writing – review & editing, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Cynthia J. Chelf: Methodology, Investigation, Formal analysis, Data curation. John P. Marinelli: Writing – review & editing, Supervision, Methodology, Investigation, Formal analysis, Data curation, Conceptualization.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.