Noise and sleep on board vessels in the Royal Norwegian Navy

The physical and psychological effects of occupational noise among seafarers: a systematic review

The aims were to highlight noise levels on board and the health effects of noise on seafarers. Data was collected from multiple databases: PubMed, Web of Science, Scopus, and Ebsco Host. Initially, the search resulted in a total of 197 articles, 16 were chosen. Several ships were found which most sailors had noise-induced hearing loss (NIHL) (n = 6). The engine room has been defined as having the highest level of noise. In addition, noise exposure was associated with hearing loss, tinnitus, sleep disturbances, communication difficulties, poor concentration, dizziness, depression, anxiety, headache, fatigue, and stress. Noise exposure is not the only factor that causes health problems: the duration of exposure while working, years of career as a maritime worker, age, lifestyle habits (smoking, alcohol consumption), and even hobbies related to loud sound (such as concert/disco attendance, listen to loud music, etc.) were associated with the adverse health effects experienced by seafarers.

The effects of occupational noise on sleep: A systematic review

Noise exposure in the workplace is one of the most common occupational hazards, which can affect sleep in the human. The effects of occupational noise can be different than that of environmental or social noise. This study aimed to conduct a systematic review on the effects of occupational noise on various characteristics of sleep. In this study, three electronic bibliographic databases (Scopus, PubMed, and Web of Science) were systematically searched up to 14 December 2022. The search algorithm included two sets of keywords and possible combinations. The first group was keywords related to occupational noise, and the second group was keywords related to sleep. A total of 2082 articles were identified in the initial search, and 2034 articles were excluded based on exclusion criteria or lacking inclusion criteria. Finally, 48 articles met the inclusion criteria and were selected for final review. Among 13 articles identified as high quality, all studies (100%) showed that noise had a significant effect on sleep among workers in various occupations. Among 17 articles with moderate quality, thirteen studies (76.47%) indicated that noise had a significant effect on sleep among workers in different occupations. Among 18 low-quality articles, fifteen studies (83.33%) showed that noise had a significant effect on sleep. 41 out of 48 studies (85.42%) found that occupational noise can negatively impact sleep among employees in various occupations. There are at least four potential pathways for this effect, including the physiological effect of daytime noise exposure, the psychological effect of daytime noise exposure, the effect of nighttime noise exposure, and the effect of hearing problems due to noise.

Sleep Architecture and Sleep-Related Breathing Disorders of Seafarers on Board Merchant Ships: A Polysomnographic Pilot Field Study on the High Seas

As seafarers are assumed to have an increased risk profile for sleep-related breathing disorders, this cross-sectional observational study measured (a) the feasibility and quality of polysomnography (PSG) on board merchant ships, (b) sleep macro- and microarchitecture, (c) sleep-related breathing disorders, such as obstructive sleep apnea (OSA), using the apnea-hypopnea index (AHI), and (d) subjective and objective sleepiness using the Epworth Sleepiness Scale (ESS) and pupillometry. Measurements were carried out on two container ships and a bulk carrier. A total of 19 out of 73 male seafarers participated. The PSG's signal qualities and impedances were comparable to those in a sleep laboratory without unusual artifacts. Compared to the normal population, seafarers had a lower total sleep time, a shift of deep sleep phases in favor of light sleep phases as well as an increased arousal index. Additionally, 73.7% of the seafarers were diagnosed with at least mild OSA (AHI ≥ 5) and 15.8% with severe OSA (AHI ≥ 30). In general, seafarers slept in the supine position with a remarkable frequency of breathing cessations. A total of 61.1% of the seafarers had increased subjective daytime sleepiness (ESS > 5). Pupillometry results for objective sleepiness revealed a mean relative pupillary unrest index (rPUI) of 1.2 (SD 0.7) in both occupational groups. In addition, significantly poorer objective sleep quality was found among the watchkeepers. A need for action with regard to poor sleep quality and daytime sleepiness of seafarers on board is indicated. A slightly increased prevalence of OSA among seafarers is likely.

Sleep deficiency, operational fatigue and the interplay of compromising factors: Analysis to aid in fatigue management

The United States Navy is a high-reliability organization that must maintain optimum performance under challenging conditions. One key challenge for sailors is obtaining sufficient sleep, which can lead to fatigue and other outcomes that compromise operational readiness. Identifying sleep issues and their causes is critical for military leaders to care for their personnel, and to make informed, risk-based operational decisions. Though previous studies in shipboard environments have implicated factors responsible for insufficient sleep (e.g. poor sleep environment and work demands), there has been less research into characterizing the complex interplay among such factors in relation to sleep and work-related fatigue outcomes. This study seeks to address this gap. Data were drawn from the Afloat Safety Climate Assessment Survey of 7617 sailors from 73 ships. The survey included demographic characteristics and measures of crew endurance (e.g. sleep, occupational impairment due to fatigue). Descriptive analyses characterized the presence and severity of sleep issues across subpopulations and operational settings (e.g. the type of ship); structural equation modelling techniques characterized and quantified the statistical associations among factors. The results indicate that sleep deficits are widespread, holding across subpopulations and operational settings. Though sleep deficits varied across subpopulations, no group obtained an average of more than 7 hr of sleep per night. Fatigue-induced occupational functional impairment was directly related to sleep deficiency, and sleep environment and job-related factors were contributors to sleep deficiency. Moreover, job-related factors emerged as potentially more consequential. Lastly, factors may exist aboard a ship that could help promote better sleep.

Exploring the Predeployment Phase of an Antarctic Expedition and the Brazilian Pre-Antarctic Training

In Antarctica, human access and presence are complex and require detailed planning and preparation in advance. The personnel of National Antarctic Programs (NAPs, i.e., scientists and support personnel, including military, civilians, and mountaineers) stay in different isolation, confinement, and extreme (ICE) environments such as ships, research stations, and scientific summer camps. Antarctica imposes harsh conditions that influence physiological and psychological responses impacting health, mood, and physical and cognitive performances. In this context, we argue why people should prepare in advance for staying in Antarctica and what to expect in ICE environments. We also spotlighted recommendations shared by different NAPs participant guides, including predeployment training. Next, we present a case study of the Brazilian Pre-Antarctic Training (PAT), a theoretical-practical training that provides technical and logistical information and assesses the adaptability and physical capacity of researchers and military personnel to perform fundamental activities in a polar environment. We evaluated and compared the individual's mood at the beginning and the end of the PAT week and observed group-specific mood changes depending on the sex, functions, and the facilities that participants accessed. Finally, we proposed that conducting training before staying in Antarctica, besides promoting conditions to better plan the voyage and knowledge of the region, can contribute to dealing with the possible mood swings during expeditions and even promote positive affect. Therefore, the psychophysiological effects of PAT are topics for further investigations.

Objective sleep assessments for healthy people in environmental research: A literature review

To date, although many studies had focused on the impact of environmental factors on sleep, how to choose the proper assessment method for objective sleep quality was often ignored, especially for healthy subjects in bedroom environment. In order to provide methodological guidance for future research, this paper reviewed the assessments of objective sleep quality applied in environmental researches, compared them from the perspective of accuracy and interference, and statistically analyzed the impact of experimental type and subjects' information on method selection. The review results showed that, in contrast to polysomnography (PSG), the accuracy of actigraphy (ACT), respiratory monitoring-oxygen saturation monitoring (RM-OSM), and electrocardiograph (ECG) could reach up to 97%, 80.38%, and 79.95%, respectively. In terms of sleep staging, PSG and ECG performed the best, ACT the second, and RM-OSM the worst; as compared to single methods, mix methods were more accurate and better at sleep staging. PSG interfered with sleep a great deal, while ECG and ACT could be non-contact, and thus, the least interference with sleep was present. The type of experiment significantly influenced the choice of assessment method (p < 0.001), 85.3% of researchers chose PSG in laboratory study while 82.5% ACT in field study; moreover, PSG was often used in a relatively small number of young subjects, while ACT had a wide applicable population. In general, researchers need to pay more attention at selection of assessments in future studies, and this review can be used as a reliable reference for experimental design.

Sleep, Sleepiness, and Fatigue on Board Faroese Fishing Vessels

PURPOSE

Faroese fishers have four times more accidents than workers on land. The aim was to understand fishers' fatigue better and how their work and sleep patterns influenced their sleepiness levels and cognitive performance.

MATERIALS AND METHODS

A total of 157 Faroese fishers wore wrist-worn actigraphs at sea and one week on land and filled in sleep and sleepiness diaries during the trip. Furthermore, a 3-minute simple reaction time (SRT) test was completed at the beginning and end of the trip. The ship's movement and noise were also logged. The actiwatch results were analysed with mixed methods repeated measures. The sleepiness registrations and performance on the SRT-test were analysed with paired t-test. The ship movements (Pitch and roll) were divided into approximately three same-sized groups (lowest 1/3, medium 1/3, and highest 1/3) and compared against the Karolinska Sleepiness Scores (KSS ranging from 1-9) ≥7 and physical tiredness (ranging from 1-9) scores ≥7. Chi-square tests were used to determine the significance of these differences. Mean sleepiness scores at sea, and the proportion of sleepiness scores ≥7 were calculated, as well as sleepiness scores as a function of the time of day.

RESULTS

While at sea, fishers had more split sleep, slept less, and had lower sleep efficiency than onshore. Sleepiness was higher at the end of the trip, and cognitive decline was found. The number of major lapses was higher at the end of the trip, but with no significant difference between the median reaction times.

CONCLUSION

The crew on-board the freezer longliner, who worked 8-8 shifts, slept the most, had the longest continuous sleep periods, the highest sleep efficiency, the lowest sleepiness levels, and the highest noise exposure during their time off.

Measurement Methods of Fatigue, Sleepiness, and Sleep Behaviour Aboard Ships: A Systematic Review

Since seafarers are known to be exposed to numerous job-related stress factors that can cause fatigue, sleepiness, and disturbed sleep behaviour, the aim of this review was to provide an overview of the subjective and objective measurement methods of these strains. Using a systematic review, 166 studies were identified within the period of January 2010 to December 2020 using the PubMed database. Of the 21 studies selected, 13 used both subjective and objective measurement methods. Six studies used only subjective and two studies only objective methods. For subjective assessment, 12 different questionnaires could be identified as well as activity and sleeping logs. Actigraphy and reaction time tests (RTT) were the most common objective methods. In single cases, electrooculography (EOG), pupillometry and ambulatory polysomnography (PSG) were used. Measurement-related limitations due to vessel-related impacts were less often reported than expected. No restrictions of daily routines on board were described, and only single-measurement disturbances due to ship movements were mentioned. The present literature review reveals that there are various routines to measure fatigue, sleepiness, and sleep behaviour on board. A combination of subjective and objective methods often appears to be beneficial. The frequent use of actigraphy and RTT on board suggests good feasibility and reliable measurements with these methods. The use of ambulatory PSG in maritime-like contexts suggests that this method would also be feasible on board.

Seafarers' Perception and Attitudes towards Noise Emission on Board Ships

Noise has long been neglected as an environmental pollutant and impairment health factor in maritime transport. Recently, acoustic pollution indicates the highest growth in transport external cost unit values. In 2020, questionnaires were submitted to seafarers to examine their noise exposure and perception on board and attitudes towards noise abatement measures. Responses of 189 participants were processed using descriptive statistics and Likert scale valuation, while their consistency was tested with indirect indicators using linear regression and correlation test. Results show that more than 40% of respondents do not consider noise as a significant environmental problem. The negative perception among respondents with ≥10 years of work experience was much lower (23.53%). Most are aware of the onboard noise harmful effects that can influence their health. Despite that, they use personal protection equipment only sometimes. A higher positive perception was recorded in groups of respondents with a university degree (90%), work experience longer than ten years (82.35%), and monthly income higher than 4000 € (70%). Respondents are not strongly motivated to participate in funding noise mitigation measures, and such a viewpoint is not related to their monthly incomes. The low awareness and motivation regarding acoustic pollution generally shown by the surveyed seafarers should be watched as a threat by the company managers. Better education and awareness are likely to be crucial to change the current state of affairs.

Habitability in Berthing Compartments and Well-Being of Sailors Working on U.S. Navy Surface Ships

OBJECTIVE

The study had two objectives: (a) to assess the prevalence of sleep-related habitability concerns in the berthing compartments of U.S. Navy surface ships and (b) to assess whether habitability issues in berthing compartments affected the sleep and well-being of crew members.

BACKGROUND

The importance of habitability for human well-being is recognized. Little is known, however, about the association between habitability factors in the sleeping/berthing compartments and sailor well-being in operational conditions.

METHOD

Fit-for-duty sailors (N = 1,269; from six ships) participated in this naturalistic and longitudinal study. Sailors reported habitability factors affecting their sleep and completed four standardized questionnaires to assess daytime sleepiness, insomnia, sleep quality, and mood. Sleep was assessed through wrist-worn actigraphy and activity logs.

RESULTS

Noise, ambient temperature, poor bedding conditions, and ambient light were the most frequently reported factors of concern. Compared to their peers with fewer complaints, sailors with more habitability-related complaints were more likely to have elevated daytime sleepiness (by 23%) and to report insomnia symptoms (145%) and lower sleep quality (21%). Sailors who reported more habitability-related issues also tended to sleep longer. Individuals with more complaints about habitability also tended to report worse mood (total mood disturbance, tension/anxiety, depression, fatigue, and confusion/bewilderment).

CONCLUSION

Habitability-related complaints are associated with sailor well-being and sleep. Future studies should expound on the various detrimental factors that degrade conditions in berthing compartments and negatively impact crew well-being.

APPLICATION

Habitability in berthing compartments of surface ships is associated with sailors' daytime sleepiness, insomnia severity, mood, and sleep attributes. Ship designers should take these findings into consideration and investigate viable and cost-effective methods to mitigate the problems we identified.

Physical influences on seafarers are different during their voyage episodes of port stay, river passage and sea passage: A maritime field study

Introduction

During a sea voyage, crew members of vessels are permanently exposed to physical stress caused by noise, vibration and heat. This study aims to describe the extent of the physical influences on board container ships and the resulting stress.

Methods

Up to four scientific investigators accompanied six sea voyages on container ships under German management. Workplace and person-related measurements for noise, vibration and climatic parameters were carried out on the vessels during the three different voyage episodes (port stay, river passage and sea passage).

Results

The interviewed seafarers reported, in decreasing order, the level of psychological stress due to vibration (80.6%), noise (71.8%) and, much less, heat (45.7%) in the workplace.

In terms of workplace-related physical measurements, the highest noise levels were found in the engine room (104 dB (A)), in the workshop (81 dB (A)) and on deck (77 dB (A)), irrespective of the voyage episode. Some noise measurements in the recreational area revealed levels above the threshold. All measured 180 vibration values were below the relevant threshold limits—with the highest values in the engine room (62 mm/s²), followed by the workshop (37 mm/s²) and the engine control room (34 mm/s²). In terms of thermal comfort, none of the measured climatic parameters differed significantly between the voyage episodes. According to the person-related physical measurements, the noise exposure was particularly pronounced among the engine room personnel with an average noise level of 96 dB (A) (often during cleaning, painting and repair work). In contrast, the deck crew and nautical officers were respectively exposed to an average level of 83 dB (A) and 77 dB (A) at work.

Discussion

A relevant stress level due to physical loads was detectable in the present study. As ship crews are exposed to the physical influences on board for 7 days a week over several months, further research is recommended to assess the long-term health effects for seafarers.

Sound Level Measurements in Berthing Areas of an Aircraft Carrier

BACKGROUND

Personnel assigned to aircraft carriers work and live in environments where hazardous noise areas and hearing recovery spaces such as sleeping areas are in close proximity to one another. Hazardous noise exposure occurring during on-duty time periods and elevated noise levels during off-duty periods in sleeping areas may be prohibiting adequate hearing recovery, thus potentially leading to hearing loss and may lead to adverse effects on sleep, leading to crew-member fatigue. This investigation characterizes Equivalent sound level (Leq) and standardized octave band center frequency noise levels according to berthing (sleeping) area location during flight operation and nonflight operation time periods on a US Navy aircraft carrier. In addition, the investigation compares noise measurements in sleeping areas to noise levels associated with auditory rest and poor sleep quality and quantity.

METHODS

Noise levels were measured in berthing areas aboard a US Navy Nimitz-class aircraft carrier during a routine at-sea period. Sixty noise measurements were taken in eight sleeping locations. Leq in decibels 'A' weighted (dBA) and noise levels from 16 to 16 000 Hz in (dB) were measured during flight operations [Leq (flt ops)] and nonflight operations [Leq (nonflt ops)]. Leq was also measured according to sleep area shipboard locations of forward (FWD) Leq (FWD), middle (MID) Leq (MID), and rear (AFT) Leq (AFT). These data were compared to the 70 dBA American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for effective quiet areas. In addition, these data were compared to noise levels associated with hearing loss and sleep parameters. Statistical analysis was conducted with R version 3.5.2 using an alpha level of 0.05.

RESULTS

Leq (flt ops) in sleeping areas was a statistically significant (P < 0.05) 6.4 dBA higher than the Leq (nonflt ops). Leq (FWD) and Leq (MID) in sleeping areas was a statistically significant (P < 0.05) 15.2 and 15.0 dBA higher, respectively, than the Leq (AFT) noise levels. Mean noise levels at standardized center (1/1) octave bands were highest between 500 and 4000 Hz, ranging from 65.2 to 69.8 dB. A total of 72% of all area Leq measurements exceeded the 70 dBA ACGIH TLV classified as effective quiet to allow for temporary threshold shift recovery. All noise measurements exceeded the World Health Organization's noise threshold where adverse effects on sleep begin.

DISCUSSION/CONCLUSIONS

Results suggest that sleeping area location in close proximity to relatively high noise sources and activities occurring on an aircraft carrier (i.e. flight operations) increase noise levels in sleeping areas. These findings raise serious concerns since high noise exposures both on duty and during off-duty/sleeping periods may inhibit auditory recovery from hazardous noise exposures. In addition, results suggest noise levels in sleeping areas are high enough to evoke negative sleep effects.

Living at Work: 24-hour Noise Exposure Aboard US Navy Aircraft Carriers

BACKGROUND

Personnel assigned to aircraft carriers are exposed to a variety of noise sources from equipment and flight deck operations for durations >12 h. Personnel work and live in environments where hazardous noise areas and hearing recovery spaces such as sleeping and relaxation areas are in proximity to one another which provides little recovery time from hazardous noise. This investigation describes noise levels measured over a 24-h period on a US Navy aircraft carrier during flight operations for different populations of aircraft carrier personnel.

METHODS

Personal noise monitoring occurred from 23 to 28 January 2014 aboard a US Navy Nimitz-class aircraft carrier during a routine at-sea period. Fifty-nine study volunteers were assigned to similar exposure groups (SEGs). The SEGs were compared to determine which groups were at greatest risk of hazardous noise exposure. Statistical analysis was conducted with SPSS version 24 using an alpha level of 0.05.

RESULTS

Mean 24-h equivalent continuous sound levels Leq(24-h) and on-duty time weighted averages (TWA(on-duty)) ranged from 71 to 127 decibels A weighted (dBA). The 80 dBA American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for 24-h noise exposure was exceeded by 93% of the study volunteers. The 85 dBA ACGIH TLV and Department of Defense Occupational exposure limit for 8-h noise exposures was exceeded by 68% of the population. Leq(off-duty) ranged from 38 to 102 dBA with 61% of the population exceeding the 70 dBA ACGIH TLV classified as effective quiet to allow for temporary threshold shift recovery. SEG 2 Flight Deck Launch and Recovery had significantly higher 24-h noise exposures than SEG 3 Damage Control Maintenance and Repair (P = 0.01), SEG 5 Supply (P = 0.01), and SEG 7 Administrative/Professional (P = 0.009). Similar results were found for TWA(on-duty) noise exposures. Median TWA(on-duty) and Leq(24-h) for SEG 2 were 16-21 dB higher than SEG 3, 5, and 7. There were no significant differences between off-duty Leq noise exposures according to SEG.

DISCUSSION/CONCLUSIONS

SEGs located on the flight deck (SEGs 1 and 2) and SEGs responsible for maintenance and repair activities (SEGs 3 and 4) supporting flight operations had the highest TWA(on-duty) and Leq(24-h). These findings raise serious concerns because high noise exposures both on- and off-duty may result in immediate acoustic trauma and development of temporary threshold shifts, which, if unresolved with auditory rest, may lead to permanent hearing loss.

Exploring Sleep-related Habitability Issues in Berthing Spaces on U.S. Navy Ships

Sleep problems are prevalent in the naval operational environment. Crewmembers attribute some of these problems to habitability-related issues in their berthing compartments. This study has two goals: first, to assess the provisions in current habitability standards used in ship design; and second, to assess the extent to which habitability factors in berthing compartments affect the sleep of crewmembers in United States Navy (USN) ships. Results from eight field studies show that environmental conditions (e.g., temperature, noise, light, air quality) affect sleep quality in berthing spaces. Despite the provisions in current standards, sleep-related habitability issues remain a concern for crewmembers in the USN. Our findings suggest that living conditions may be improved in berthing compartments by revising current standards. We have identified three areas for improvement: noise (both continuous and intermittent), temperature within the compartment, and designing berthing compartments according to the organizational structure of the ship.