Background

Sleep is essential for health, growth, psychology, motor development and cognitive function [7]. Sleep duration is variable as it is dependent on the sleep cycle. We sleep for 4–6 cycles each night. Each cycle lasts from 70 to 120 min. Each cycle consists of four different stages, from light sleep to deep sleep. Unable to reach stages 3 and 4 in each cycle of sleep affect memory, thinking, creativity and cognitive function.

According to the American Academy of Sleep Medicine, “insomnia involves difficulty falling asleep or staying asleep, or regularly waking up earlier than desired, despite allowing enough time in bed for sleep” [1]. Insomnia is a big problem as it affects 25–50% of children [7]. Insomnia can be due to sleep apnoea, nocturia, restless leg syndrome (rare in children) or environmental factors [7]. Sleep hygiene improves the routine and the sleep environment. Sleep hygiene helps to initiate sleep and maintain sleep through the night without the need for medication. A cross-sectional study conducted in the USA back in 2007 found that 81% of cases where children presenting to a medical professional for insomnia led to medical prescription [10]. Some of the medications are unlicensed for children, affect the brain and have side effects. Behavioural therapy was prescribed for only 22% of the cases. Highest occurrence of insomnia was found in children between 6 and 12 years of age [10].

A review that was published in 2006 found that behavioural therapy is effective in children below 5 years of age [5].

In this interventional study, we are analysing the effectiveness of sleep hygiene videos as a single therapy in children from 10 to 11 years of age (grades 5 and 6), with the aim to improve sleep quality and subsequently cognitive function.

Methods

The focus of the study was to support children aged 10 and 11 years in establishing a good sleep hygiene using a behavioural model of introducing sleep hygiene principles by presenting an effective and clear message that children in this age can understand in the form of animated cartoons. The utility of this approach is assessed through a retrospective self-completing questionnaire.

Subjects’ characteristics

Two different grades in two different schools across Leeds city (England) participated. The subject of the study was 5th- and 6th-grade students. Thirty students per class and subsequently a total of sixty students per school were expected to be included in the study. There were no exclusion criteria.

Design of the videos

The videos were made with Adobe After Effects and Character Animator. Language and animations were child friendly. Two videos were created. The first video was called “The importance of sleep”, and it explained the importance of sleep, the different stages of sleep with the features of each stage, the different causes of insomnia and tips on how to initiate and maintain sleep [11]. The video ended up with an open question on what you would do to improve your sleep. The second video was called the “Big sleeping book”, and it demonstrated different scenarios children could find themselves in when struggling to sleep, followed by advice on how to deal with each scenario such as having a new baby in the house, having a noisy neighbour or stopping video games before bed. The first video was 3.27 min. The second video was 2.44 min. The videos were intentionally short to facilitate a high engagement rate.

Design of the questionnaire

The questionnaire was a self-completing questionnaire that was adapted from the Pittsburgh Sleep Quality Index Questionnaire [2]. The questionnaire was modified to be child friendly. It consisted of 30 statements that assess sleep duration, sleep disturbance, sleep latency, daytime dysfunction due to sleepiness, sleep efficiency, subjective sleep quality and cognitive function. The children had four options to choose from: rarely, sometimes, often and almost always. Rarely was described as none or 1–3 times a month, sometimes as 1–2 times a week, often as 3–5 times a week and almost always as 6–7 times a week. Students filled the questionnaire by ticking the relevant box.

Implementation and data collection

SENCOs (Special Educational Needs Coordinator) were contacted at seven schools across Leeds to acquire approval to conduct the research study at their school in October 2021. Four schools showed interest, but due to staff shortages during the COVID-19 pandemic and site-specific COVID-19 restrictions from October 2021 until February 2022, we were only able to conduct the research in 2 schools in April and May 2022. One school was in the north, and the other was in the East of Leeds. The latter school is in one of the low socioeconomic areas of Leeds with high deprivation. I visited the schools and interacted with SENCOs and students explaining the study design. The students filled the questionnaire before watching the two videos and repeated the questionnaire after 2–3 weeks of watching the video; this interval was to give the children the time to implement and reflect on their sleep hygiene. The session was incorporated as part of their PSHCE lesson (personal, social, health and citizenship education).

Statistical analysis

The data from the questionnaire were answered using a Likert scale. The data was transferred to an Excel sheet for analysis. A scoring from 0 to 3 represented positive statements (0 for rarely, 1 for sometimes, 2 for often and 3 for almost always). A scoring of 0 to − 3 was used to represent negative statement (0 for rarely, − 1 for sometimes, − 2 for often and − 3 for almost always). For positive statements, 3 represented the greatest function, and 0 represented the greatest dysfunction. In contrast, when considering negative statements, 0 represented the greatest function, and − 3 represented the greatest dysfunction. Data was grouped into seven domains (Tables 1 and 2) which were sleep duration, sleep disturbance, sleep latency, daytime dysfunction due to sleepiness, sleep efficiency, subjective sleep quality and cognitive function. One statement was removed from the study as multiple students did not understand its meaning, so 29 statements were analysed instead of 30 (Tables 1 and 2). The statement was “I feel unlikely to sleep after having a nap/ sleep”. One statement matched two domains. The statement was “I wake up while sleeping”, and the response to it was analysed under sleep disturbance and sleep efficiency. As the statements are categorical questions, a table chart was used to represent the results. Percentage of change was calculated based on the difference in score of each domain between the first and the second questionnaire. We employed the Wilcoxon signed-rank test to determine the significance of the outcomes of each domain for each school. We employed critical values corresponding to p < 0.05. The critical values were taken from the statistical resource real-statistics.com (Real Statistics using Excel, [12]).

Table 1 The data analysis of the first school (East of Leeds) for grade 5 and grade 6
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Table 2 The data analysis of the second school (North of Leeds) for grade 5 and grade 6
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Results

Results of the first school in the East

In grade 5, 25 students filled the questionnaire. One questionnaire was not analysed as not all the statements were answered. In grade 6, 28 students filled the questionnaire. Three questionnaires were not analysed as some of the statements were not answered (Fig. 1).

Fig. 1
figure 1

Flowchart of questionnaires included in the analysis

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Students who were not present in school in the first phase of the study were asked not to complete the questionnaire in the second phase.

In total, 49 completed questionnaires were analysed. There was a positive change in sleep duration by 13.6%, sleep disturbance by 10.9%, sleep latency by 22%, daytime dysfunction due to sleepiness by 8.7%, sleep efficiency by 10% and subjective sleep quality by 6% (Table 3). There was a negative change in cognitive function by 1.3%. We employed the Wilcoxon signed-rank test to establish the significance of these changes. The null hypothesis (p < 0.05) was rejected for sleep duration, sleep disturbance, sleep latency, daytime dysfunction due to sleepiness, sleep efficiency and cognitive function domains (Table 3). We could not reject the null hypothesis (p < 0.05) for subjective sleep quality (Table 3). Analysing each domain, the sleep disturbance and sleep latency outcomes were furthest away from the W-critical (< 20% of W-critical) which suggest more substantial impact.

Table 3 The total score of the main 7 domains depending on the type of the statement used in the first school with the % of change (East of Leeds)
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Results of the second school in the North

In grade 5, 25 students filled the questionnaire. Six questionnaires were not analysed as some of the statements were not answered. In grade 6, 28 students filled the questionnaire. Two questionnaires were not analysed as some of the statements were not answered.

Students who were not present in the first phase of the study and were asked not to complete the questionnaire in the second phase (Fig. 1).

In total, 45 completed questionnaires were analysed. There was a positive change in sleep duration by 5.9%, sleep disturbance by 6.7%, sleep latency by 3.7%, daytime dysfunction due to sleepiness by 1% and sleep efficiency by 0.6% (Table 4). There was a negative change in subjective sleep quality by 4.9% and cognitive function by 2.2%. We employed the Wilcoxon signed-rank test to establish the significance of these outcomes. The null hypothesis (p < 0.05) was rejected for sleep duration, sleep disturbance and sleep latency and cognitive function and subjective sleep quality domains. We could not reject the null hypothesis (p < 0.05) for daytime dysfunction due to sleepiness and sleep efficiency (Table 4). Analysing each domain, the sleep disturbance was furthest away from the W-critical (< 30% of W-critical) which suggest more substantial impact.

Table 4 The total score of the main 7 domains depending on the type of the statement used in the second school with the % of change (North of Leeds)
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Discussion

Poor sleep hygiene is a common cause of sleep difficulties; it is recognised that poor sleep hygiene affects children in various ways presenting as behavioural difficulties, poor concentration and daytime sleepiness. The focus of the study was to support children of a certain age group in establishing a good sleep hygiene using a behavioural model of introducing sleep hygiene principles. There are established psychometric parameters for adults in order to assess sleep function, but these are absent for children. One published study assessing the use of the well-established adult self-assessment questionnaire “The Pittsburgh Sleep Quality Index (PSQI)” in healthy children found that PSQI is a very liable tool to assess sleep function in children [8]. We adapted the PSQI questionnaire and made it more child friendly in order to facilitate self-assessment in children. The PSQI questionnaire has seven domains of assessment which are sleep duration, sleep disturbance, sleep latency, daytime dysfunction due to sleepiness, sleep efficiency, subjective sleep quality and the use of sleep medication [2]. In the American Academy of Sleep Medicine (AASM), sleep duration is defined as “the regular total hours to promote optimal health”, sleep disturbance is defined as “ any situation that interferes with sleep”, sleep latency is defined as “ the amount of time requires to fall asleep once settling down for the night”, daytime dysfunction is defined as “the role of sleep in daily function”, sleep efficiency is defined as “the total amount of time that the person slept divided by the total amount spent in bed” and subjective sleep quality is defined as “the subject aspect of sleep like depth and restfulness” [3]. The domain of sleep medications, which is also part of the PSQI, was not taken into consideration in our study since we assessed sleep function in healthy children in normal stream schools. In children with ADHD, ADHD stimulant medications such as methylphenidate can affect the sleep initiation by delaying it by 30 min [9]. Based on this, we used six of the seven domains of the PSQI [2]. We aimed to assess cognitive function in our study by involving a child psychologist. This would provide the opportunity to adapt part of the questionnaire to assess the cognitive development. Due to COVID-19 restrictions, we were not able to arrange this. However, cognitive function was the seventh domain in our study with two questions serving as indicators rather than determinants. A 2- to 3-week duration between the questionnaires was given to allow the students time to implement the changes identified and discussed. At least 2-week duration is needed to differentiate trainset from permanent impact [2]. We had a total number of 94 completed questionnaires from two schools. In the East of Leeds School, there was significant improvement in five domains which were sleep duration, sleep disturbance, sleep latency, daytime dysfunction due to sleepiness and sleep efficiency. The positive change in subjective sleep quality was determined to be insignificant. In the North of Leeds School, there was significant improvement in three domains which were sleep duration, sleep disturbance and sleep latency. The change in outcomes related to daytime dysfunction due to sleepiness and sleep efficiency was small in the second school and deemed insignificant by the Wilcoxon signed-rank test. The negative change in subjective sleep quality was determined to be significant. Subjective sleep quality is difficult to assess in adult, and it varies between individuals and its culture affected [3]. The outcomes in the second school were less desirable, and this could be related to the students taking the second phase of this study after the spring half-term holiday, and in their assessment week (exam week), both of which can be confounding factors. There was a negative change in outcome in the cognitive domain in both schools that was deemed statistically significant. The cognitive domain was assessed via two statements about memory and concentration. This was not a full cognitive assessment. Utilising a detailed comprehensive cognitive assessment tool with the consultation of a child clinical psychologist could clarify this outcome.

Overall, there was significant improvement in multiple domains in sleep functions in both schools. A published review in paediatric sleep medicine found that there is limited awareness of childhood sleep function between health professionals [6]. There is limited research in the sleep field in children, and it is confined to children with ADHD and autism spectrum disorder. We could not elicit any published studies about the effect of behavioural sleep intervention in healthy children at school age. A published study in children with ADHD from 5 to 12 years of age with sleep difficulties found that behavioural sleep intervention was effective in improving sleep and behaviour [4].

To our knowledge, this is the first study to assess the effect of behavioural modification of sleep principles using a video resource; further studies with a larger sample size will be required to investigate the full potential of this approach. Having a tool that is easily accessible to schools, SENCO, parents and children may have a substantial impact on sleep hygiene.

We are aware that the study sample was relatively small. We would have liked a larger number of students to be included in the study, but there were difficulties in school engagement during the COVID-19 pandemic and subsequent restrictions. Parents should also be engaged as they play an instrumental part in environmental modifications; this will be considered in the second phase of the study.

Conclusion

Behaviour sleep intervention has a significant and long-term impact on children. Introducing child-friendly sleep hygiene videos can improve a child’s sleep and health. Further studies are needed with a larger sample size.