INTRODUCTION
Patients admitted to hospitals often encounter moderate to high levels of noise, leading to disturbance [1] in their sleep patterns. Patient feedback indicates that various factors, including pain, vital sign monitoring, and diagnostic tests, significantly contribute to sleep disruptions during their hospital stay [2]. Timely and necessary vital sign assessments and examinations conducted early in the morning are integral to formulating an effective treatment plan for patients. In addition, there are concerns about illness, physical discomfort, and ambient noise [3,4] compound sleep disturbances among hospitalized individuals. In the context of shared accommodation (e.g., the four- or six-bed rooms commonly found in South Korean hospitals) patients frequently identify noise from the snoring or groaning of other patients, toilet flushing, the movement of medication carts, and telephones usage [1,5]. Given that many hospitals in South Korea house multiple patients in a single room, the potential for heightened sleep disturbances becomes more pronounced.
Despite the findings of studies on the light environment and lighting control [6,7], to date, there has been little research on the relationship between lights-off time in hospital rooms and sleep quality. Lights-off time in wards needs to be studied since it might be related to patients’ sleep. For example, a late lights-off time might delay their sleep-wake cycle, given the phase response curve to light [8]. On the other hand, while a late lights-off time may disturb patients’ sleep, it may be helpful to nursing care activities [9]. In contrast to the USA, where single-bed rooms are common, six-bed rooms are typical in South Korea. Patients in six-bed rooms in South Korea cannot control their individual sleep-wake cycle due to their lack of control over the lights-off time. However, no studies have examined which lights are turned off in ward rooms in South Korean hospitals and the effect on patients.
Previous study reported that 17 hours of activity are needed for 7 hours of sleep [10]. In addition, based on the two-process model, which showed the interaction of the homeostatic process (Process S) and a circadian pace-maker (Process C) [11,12], an early bedtime does not guarantee early falling sleep since a fluent period of wakefulness (sleep pressure-homeostatic drive) is needed to fall asleep [13]. Consequently, if the lights-off time is too early, some people will likely sleep earlier than usual. Even though there are no reports on South Korea’s lightsoff time in ward rooms, it is usually 9:30 PM or 10:00 PM [14]. It is generally recommended that older adults sleep for 7-8 hours per night [15]. If the lights are turned off by 9:00 PM to go to sleep, it is anticipated that older adults will wake at 4:00 AM to 5:00 AM. This phase advance sometimes results in older people experiencing an advanced type of Circadian rhythm sleep-wake disorder [16]. It is, therefore, necessary to study whether the current lights-off time for patients’ sleep or nursing care activities is too early or appropriate.
This study aimed to examine how nursing professionals perceive the current lights-off time in wards and whether their perceptions on the current lights-off time can be changed when considering people’s usual bedtimes. Thought the survey, we tried to identify the optimal time for patients’ sleep or nursing care activities. In addition, we explored whether nursing professionals’ characteristics may be associated with the perception on the lights-off time when considering people’s usual bedtimes.
METHODS
Participants and procedure
An anonymous online survey was conducted among shiftworking nursing professionals in Asan Medical Center from July 26 to August 17, 2023. Nursing professionals who wanted to participate in this survey could do so by checking “agree” in response to the agreement question linked in an advertisement posted on the Center’s intranet. When respondents had completed the survey, they received a 5,000 KRW gift coupon for their participation. We collected participants’ demographic information, including age, sex, years of employment, marital status, and workplace. In addition, we asked respondents whether they had any relevant personal information such as past psychiatric history or current psychiatric distress. The Institutional Review Board of Asan Medical Center approved the study protocol (2023-0858).
The survey form was designed to gather participants’ responses in a sequential manner. In the first section, respondents were prompted to indicate the typical lights-off time in the wards where they worked. They were also asked whether they regarded the current lights-off time as too early, appropriate, or too late, and to provide reasons for their opinions. The second section required participants to respond to rating scales to determine their psychological status. In the third section, they were asked about their views on the appropriateness of the current lights-off time when considering people’s usual bedtimes. They were also asked to specify what they deemed to be an appropriate lights-off time for patients’ sleep and for nursing care activities when taking into account people’s typical bedtimes.
Measures
Insomnia Severity Index
The Insomnia Severity Index (ISI) was developed to measure an individual’s insomnia severity [17]. It is a brief self-rating scale that contains seven items scored on a Likert scale (0-4). Total scores range from 0 to 28, with a higher total score indicating a more severe degree of insomnia. The validated Korean version of the scale was used in this study [18] and was checked for reliability, achieving a Cronbach’s alpha of 0.844 for this sample.
Patient Health Questionnaire-9
The Patient Health Questionnaire-9 (PHQ-9) was developed to assess the severity of an individual’s depressive symptoms [19]. It is a brief self-rating scale that contains nine items scored on a Likert scale (0=not at all to 3=nearly every day). Total scores range from 0 to 27, with a higher total score indicating a higher degree of depression. The validated Korean version was used in this study [20] and was checked for reliability, achieving a Cronbach’s alpha of 0.784 for this sample.
Dysfunctional Beliefs and Attitudes about Sleep-16
The Dysfunctional Beliefs and Attitudes about Sleep-16 (DBAS-16) was developed to assess individuals’ sleep-related dysfunctional beliefs [21]. It is a self-report rating scale that contains 16 items scored from 0 to 10. The final score is calculated as an averaged score of all items, with higher averaged scores indicating a higher degree of dysfunctional beliefs about sleep. The validated Korean version was used in this study [22] and was checked for reliability, achieving a Cronbach’s alpha of 0.902 for this sample.
Sleep indices on lights-off time
Calculating the time variables for lights-off time was achieved by averaging the usual times provided by participants. If a participant reported a current lights-off time of between 9:00 PM and 10:00 PM, the estimated lights-off time was registered as 9:30 PM. To conduct the statistical analysis, this time variable was transformed into numeric variables. For instance, 30 minutes (half an hour) was converted to 0.50; thus, 9:30 PM was transformed into 9.5.
Discrepancy between Desired Time in Bed and Desired Total Sleep Time Index
Desired total sleep time (dTST) was estimated on the basis of participants’ response to the question, “How many hours do you like to sleep each day when you are not doing shift work?” Desired time in bed (dTIB) was estimated on the basis of the response to the question, “Between what hours do you like to sleep when you are not doing shift work?” [13]. The Discrepancy between Desired Time in Bed and Desired Total Sleep Time (DBST) Index was calculated as [dTIB-dTST] [13].
In this study, we also estimated the expected DBST Index of non-participants. The question, “How long do you think other people like to sleep each day?” was used to estimate the expected dTST and “Between what hours do you think other people like to sleep?” was used to estimate the expected dTIB. The expected DBST Index of other people was calculated as the expected dTIB of other people-expected dTST of other people. This index was included in this study to allow participants to consider the usual bedtimes of others.
Statistical analysis
Demographic characteristics, continuous variables, and rating scale scores were summarized as mean±standard deviation, while categorical variables were presented as n (%). The level of significance was set at two-tailed values of p<0.05.
Initially, participants were categorized into three groups (too early, appropriate, and too late), and the Kruskal-Wallis test was employed to explore differences in continuous variables among these groups. A post-hoc analysis was conducted using the Mann-Whitney test. Fisher’s exact test was utilized to investigate differences in categorical variables among the three groups.
Subsequently, we compared the proportion of responses indicating agreement that the current lights-off time was too early before and after considering the usual bedtimes of others. McNemar tests were performed using a 2×2 matrix (too early group vs. appropriate and too late groups). A repeated measures analysis of variance test was conducted to explore changes from the current lights-off time to the appropriate time for turning off lights (for patients’ sleep and nursing care activities) when considering the usual bedtimes of others.
Finally, participants were categorized into two groups (too early and appropriate) on the basis of their agreement that the current lights-off time was too early when considering the usual bedtime of others since no participants responded with “too late” to the question. Between these two groups, a student’s t-test and the χ2 test were conducted to explore differences in the continuous and categorical variables. The Pearson’s correlation coefficients were examined among the clinical variables and rating scales scores. The statistical analysis was carried out using SPSS version 21.0 (IBM Corp., Armonk, NY, USA).
RESULTS
A total of 212 individuals accessed the survey, with 208 agreeing to participate and 202 shift-working nursing professionals completed the survey. The subgroup analysis was conducted using 159 participants whose responses were specifically related to early lights-off times in ward rooms before 11:00 PM. The participants had a mean age of 30.1±5.7 years, the mean years of employment of 6.9±5.6, and 96.2% were female.
Categorizing responses to the question, “Do you think that the current lights-off time is too early in your unit?” into three groups (too early, appropriate, or too late) (Table 1), 88.7% considered it appropriate, 6.9% considered it too early, and 4.4% considered it too late. Comparing the “too early” group to the “appropriate” group, participants in the former were significantly older and had longer years of employment. The lights-off time for the “too early” group was significantly earlier than that for the “too late” group. The “appropriate” group had a significantly higher proportion of single individuals compared to the “too early” or “too late” groups. No significant differences were observed in terms of working place, past psychiatric history, current psychiatric distress, or rating scale scores among the three groups.
Considering people’s usual bedtime, the proportion of responses categorizing the current lights-off time as “too early” increased from 6.9% to 28.3% (p<0.001) (Table 2). The responses to the appropriate time to turn off the lights changed from 9:46±29 PM to 10:06±0:42 PM for patients’ sleep and 10.22±0:46 PM for nursing care activities (all, p<0.001) when considering people’s usual bedtimes. Categorizing participants into two groups based on responses to the current lights-off time as “too early” and “appropriate” while considering people’s usual bedtime, the ISI score was significantly higher among participants who responded that current light off time is too early after considering usual bedtime of other people (p=0.007) (Table 3).
In the correlation analysis, years of employment was not significantly correlated with any of the rating scale scores. The ISI score was significantly correlated with PHQ-9 (r=0.697, p=0.001) and DBAS-16 (r=0.472, p=0.048).
DISCUSSION
In this study, we found that 88.7% of nursing professionals considered the current lights-off time to be appropriate, even though it was at 9:46±0:29 PM. However, when prompted to consider people’s usual bedtime, there was a significant increase in the proportion of responses indicating that the lightsoff time was too early. Furthermore, respondents believed that the lights-off time should be postponed to 10:06±0:42 PM and 10.22±0:46 PM for patients’ sleep and nursing care activities, respectively. Ultimately, insomnia severity was significantly higher among nursing professionals who responded that current lights-off time was too early when considering people’s usual bedtimes.
Although the sample size was small (n=11), the nursing professionals who categorized the current lights-off time as “too early” were significantly younger and had significantly longer work experience than those who deemed it “appropriate” (Table 1). The higher proportion of single individuals in the “appropriate” group aligns with this finding. Longer tenure in wards may lead individuals to recognize that many patients struggle to sleep if the lights are turned off earlier. Conversely, younger nursing professionals may perceive the need for an earlier lights-off time to alleviate the workload associated with caring for patients who are awake. Despite the current lightsoff time for the “too early” group being relatively earlier than that for the “too late” group, there was no discernible difference between the “too early” and “appropriate” groups.
The proportion of responses categorizing the current lightsoff time as “too early” increased from 6.9% to 28.3% when other people’s bedtimes were considered, which suggests that healthcare workers may not have contemplated the usual bedtimes of individuals when assessing inpatients’ bedtimes. In addition, nursing professionals said that the lights-off time should be postponed to 10:06±0:42 PM for patients’ sleep and 10.22±0:46 PM for nursing care activities. These findings highlight the possibility that the current lights-off time in the hospital can be seen as earlier than might be expected.
Numerous factors contribute to the early lights-off time, as indicated in Supplementary Table 1. Early schedules for diagnostic tests, vital sign checks, blood sampling, or physical examinations before rounds are among the reasons. Moreover, the prevalence of six-bed rooms in the healthcare system in South Korea, in which caregivers occasionally share a small side-bed, adds complexity. In six-bed rooms, each individual prefers to fall asleep at their own time, posing a potential challenge to delaying the lights-off time in such settings.
In general, an early bedtime has been associated with an increased likelihood of taking sleeping pills [23]. This phenomenon has been observed in cancer patients [24], who are prevalent in hospital settings. Among cancer patients, those who retire to bed early and express a desire for early administration of sleeping pills to facilitate easier sleep often report lower satisfaction with the sleeping pills [24]. Conversely, a longer sleep onset latency is linked to a shorter duration between wake-up time and bedtime (WTB) [10]. Hence, we can speculate that patients inclined toward earlier bedtimes may be more prone to taking sleeping pills to achieve easier sleep, although an early bedtime, based on the two-process model, does not guarantee an early onset of sleep [10]. This may offer insights into why the prescription rates for sleeping pills increase during hospital stays and why some patients persist in taking them post-discharge [14]. In an effort to reduce the prescription rates for sleeping pills, we previously implemented the Sleep Education and Hypnotics Reduction Program for both inpatients [25] and cancer patients [26] in the hospital.
Between the “too early” and “appropriate” groups, after considering people’s usual bedtimes, there were no significant differences in age or years of employment, which were significant factors before considering people’s usual bedtimes. In addition, there was no significant difference in the current lightsoff time between the two groups. However, insomnia severity was significantly higher among the “too early” group than the “appropriate” group. This suggests that nursing professionals with insomnia may perceive the current lights-off time as too early after considering people’s usual bedtimes. This unexpected result contrasts with the anticipated outcome as individuals with insomnia typically go to bed earlier to facilitate early sleep onset [10]. Consequently, it is plausible that nursing professionals experiencing insomnia may prefer an early bedtime, assuming that patients also need to retire early.
Several explanations for this unexpected outcome are plausible. First, given healthcare professionals familiarity with medical knowledge, they may automatically recognize that an early bedtime does not guarantee early sleep onset. Furthermore, individuals with insomnia, drawing from their own experience of sleeplessness, may readily identify the lights-off time as too early. Second, shift-working nursing professionals, who are often prone to sleep disturbances, may inherently value a well-regulated sleep-wake cycle and, from their experience of insomnia, may already be aware that an early bedtime does not guarantee early sleep onset.
In this study, we incorporated variables such as the DBST and expected DBST indexes, although they did not significantly predict responses to the current lights-off time as too early. These variables were included with the aim of prompting nursing professionals to consider the usual bedtimes of other people. It is worth noting that the idea of an expected DBST Index of other people was introduced for the first time in this study. Individuals experiencing sleep disturbances may inaccurately perceive their own bedtime and the DBST Index, which measures the discrepancy between dTIB and dTST, could serve as a variable indicative of sleep-related attention bias [27]. Our hypothesis suggested that sleep-related attention bias might be alleviated by considering the DBST indexes of other people. While we did not find a significant association between asking for the DBST indexes of other people and participants’ responses, we included this variable to enhance participants’ comprehension of other people’s usual bedtimes. Further investigation is warranted to discern whether the DBST Index can be distinguished from the concept of the expected DBST Index of other people.
This study has several notable limitations that warrant consideration. First, the study focused exclusively on shift-working nursing professionals and did not provide a direct assessment of whether an early bedtime is uncomfortable for patients. Future research involving direct patient perspectives and experiences is crucial to better understand the implications of early lights-off times on patient well-being. Second, the subgroup analysis was based on responses where the current lightsoff time was earlier than 11:00 PM. The lack of a universally defined threshold for what constitutes an early lights-off time introduces ambiguity into the interpretation of the results. A standardized criterion for early lights-off times would enhance the precision and generalizability of future investigations. Third, the study’s setting in a single tertiary-level general hospital in South Korea raises the possibility that the observed early lightsoff time was influenced by cultural characteristics specific to this region. Cultural nuances and healthcare practices can significantly impact sleep-related behaviors and perceptions. Consequently, caution should be exercised when generalizing these findings to other cultural contexts. Moreover, the study’s exclusivity to a single hospital may limit the external validity of the results. Hospital-specific factors, such as institutional policies, patient demographics, and staff characteristics, can vary widely across different healthcare settings. Replicating this study in diverse healthcare environments and cultural contexts would enhance the generalizability of the findings. Last, the ISI score of nursing professionals, which was found to be a significant predictor of the appropriateness of the ward’s lights-off time, should be examined from the perspectives of a confounding factor or spurious correlation. A more detailed further study is needed to explore the real effect of the nursing professionals characteristics on their perceptions on the lights-off time.
In conclusion, the study underscores the need to reassess lights-off times in ward rooms while considering people’s usual bedtimes. It is important to note that possible cultural differences between Korea and other countries would need to be taken into account during this re-evaluation. The findings of this study have broad implications, shedding light on key factors such as the perception of lights-off time, variations in age and experience among nursing professionals, the impact of insomnia on their perspectives, and the dynamics of patients’ sleep and nursing care activities. Moreover, the study highlights the challenges faced by shift-working nursing professionals. Addressing these implications could pave the way for the development of more patient-centered and effective sleep schedules in healthcare settings.
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