Parental sleep when their child is sick: A phased principle‐based concept analysis

Abstract Sleep is a common challenge for parents with sick children and can impact parents' health, wellbeing, and caregiving responsibilities. Despite the vast research around parental sleep when their child is sick, the concept is not clearly defined. A phased principle‐based concept analysis that includes triangulation of methods and quality criteria assessment was used to explore how the concept is described, used, and measured in the current literature. The aim was to analyse and clarify the conceptual, operational, and theoretical basis of parental sleep when their child is sick to produce an evidence‐based definition and to identify knowledge gaps. A systematic literature search including databases CINAHL, Embase, MEDLINE, PsychARTICLES, PsychINFO, Pubmed, Scopus and Web of Science, identified 546 articles. The final dataset comprised 74 articles published between 2005 and 2021 and was assessed using a criteria tool for principle‐based concept analysis. Data were managed using NVivo, and thematic analysis was undertaken. A precise definition is not present in the literature. Various tools have been used to measure parents' sleep, as well as exploration via interviews, open‐ended questions, and sleep diaries. The terminology used varied. Parental sleep when their child is sick is interrelated with other concepts (e.g., stress). A recommended definition is offered. A conceptual understanding of parental sleep when their child is sick will help to guide translational research and to conduct studies critical to clinical practice and research. Future research includes developing a measurement tool for parental sleep when their child is sick to be used in study design and future interventions.


| INTRODUC TI ON
Sleep is a physiological process and one of the most fundamental human needs (Zhu et al., 2018). It is essential for health, wellbeing, and performance (Lee-Chiong, 2008). According to Merriam Webster, sleep is "the natural, easily reversible periodic state of many living things that is marked by the absence of wakefulness and by the loss of consciousness of one's surroundings, is accompanied by a typical body posture (such as lying down with the eyes closed), the occurrence of dreaming, and changes in brain activity and physiological functioning, is made up of cycles of non-REM sleep and REM sleep and is usually considered essential to the restoration and recovery of vital bodily and mental functions" (Merriam-Webster, 2021).
Parents' sleep can be affected for multiple reasons (Palmstierna et al., 2008). A child who is sick can demand more supervision and care, making sleep disturbance a common challenge among parents of sick children (Stickland et al., 2016). Concerns about the child's diagnosis, treatment, and care can be a significant source of worry and anxiety (Cousino & Hazen, 2013;Stremler et al., 2011), adding to daily hassles and therefore affecting sleep quality. Sleep not only affects parents' wellbeing but also their child's care as symptoms of sleep loss may limit their parents' ability to meet their child's needs . Negative parenting behaviours, such as high stress, low self-efficacy, and greater irritability in parent-child interactions have been associated with sleep loss. It remains important for parents to be able to rest and sleep so they can restore energy to be able to meet their child's health needs. Sleep is therefore important for the parents' own physical and emotional health, their ability to cope with the illness event, support their child and other family members, participate in decision-making and to maintain relationships .
Despite the impact that parental sleep can have on the parents themselves, the sick child, and the whole family, parental sleep when their child is sick is a fairly recent research area that requires more attention Mörelius & Hemmingsson, 2013).
An integrative review on parents' experiences of sleep when they stay overnight with their hospitalised child supports the need to clarify the meaning of sleep among parents (Løyland et al., 2019).
Considering the growing literature in this field, it is important to define a common language to use when performing research in this area. This will increase the possibility to compare studies, perform meta-analyses, draw conclusions, and develop and provide evidenced-based care in the future.
Principle-based concept analysis (Penrod & Hupcey, 2005) reviews the strengths and limitations of the present state of a concept in the scientific literature and can assist the clarification and development of the concept parental sleep when their child is sick.
It is the analysis of a concept according to four broad philosophical principles: epistemological, pragmatic, linguistic, and logical (Smith & Mörelius, 2021). Epistemology is concerned with how the concept is defined and differentiated within the literature (Waldon, 2018).
The pragmatic principle considers the concept's usefulness and whether it has been operationalised (Smith & Mörelius, 2021). The linguistic principle evaluates the consistency of use and meaning of a concept within the literature, and the context is also considered (Waldon, 2018). The logical principle considers the theoretical integration of the concept with other related concepts (Ruel & Motyka, 2009). Clearly defined conceptual boundaries are essential to prevent loss of meaning caused by conflicting attributes when positioned with other concepts in a theoretical framework (Ruel & Motyka, 2009). A principle-based concept analysis reduces the data (literature) through initially reviewing and summarising the four principles (Smith & Mörelius, 2021). The conceptual components (the construction of the concept) are then explored via the preconditions (phenomena or events that precede an instance and that influences the concept), characteristics/attributes (frequent words or expressions used to describe the experience of the concept), and outcomes (the consequences that follow the occurrence of the concept) (Waldon, 2018). The final product is a theoretical definition based on integrating the summaries of the four principles and the conceptual components or highlighting an existing definition that covers these aspects.
The purpose of this study was to analyse and clarify the concept of parental sleep when their child is sick by exploring how it is described and used within the literature and to introduce a theoretical definition.

| Study design
A phased principle-based concept analysis on parental sleep when their child is sick, according to Smith and Mörelius (2021), was followed. This comprehensive approach to conducting a principlebased concept analysis is systematic and enhances transparency, rigour, and replicability. The team's expertise was also considered. A varied research team aids to advance the transference of knowledge across disciplines (Smith et al., 2018), which applies to the principle-based concept analysis and promotes exploring multidisciplinary perspectives in understanding a concept (Penrod & Hupcey, 2005). The research team included a wide range of disciplines from health psychology, implementation science, neonatology, and paediatrics.

Phase 1; stage 1: determine the concept of interest
The concept of interest was parental sleep when their child is sick.
The terms "parental sleep when their child is sick" and "concept" are used interchangeably in this review. This concept has been identified in the literature without a precise definition (Løyland et al., 2019) and is an area that requires further consideration Mörelius & Hemmingsson, 2013).

Phase 1; stage 2: develop a protocol
An a priori protocol was developed to outline the databases to search, the inclusion/exclusion criteria, data extraction, quality criteria, and synthesis. All of the authors were provided with the protocol.

Phase 1; stage 3: systematic literature search
To determine the scope and range of the literature, a systematic review search was conducted based on the Centre for Reviews and Dissemination guidelines from the University of York, UK (CRD, 2009;Dehghani et al., 2018).
An experienced research librarian was consulted on the databases and keywords to use as recommended (Aromataris & Munn, 2017). This concept constitutes several important keywords.
Keywords were used in all databases, and when possible, controlled terms were used. Box 1 details the variation of the keywords searched.
One author conducted the searches, and the results were exported to Endnote (The EndNote Team, 2013) to manage the process. The searches were limited to English and academic journals/ peer-reviewed journals if available. No time restriction was used in order to capture relevant studies and an overview of the concept over time (Zhu et al., 2018). In paediatric nursing, it is important to have a generic perspective and to find commonalities and support possibilities that suit parents irrespective of the child's disease or diagnosis (Leeman et al., 2016;Meltzer & Moore, 2008).
Therefore, we did not restrict the search to particular conditions.
The initial search was carried out in June 2019 and updated in September 2021. Table 2 outlines the criteria and the databases searched.
Phase 1; stage 4: screen articles Figure 1 provides the screening process followed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). To assure quality, two authors simultaneously and independently carried out the screening process by initially reading the title and abstracts and sequentially excluding records according to the inclusion and exclusion criteria. When inclusion or exclusion could not be determined based on title and abstract, the article BOX 1 Search strategy Core databases (CINAHL, PsychInfo, PsychArticles, Embase, Medline) 1. Parent* 2. mother* 3. father* 4. "sleep quality" 5. "quality of sleep" 6. "sleep disrupt*" 7. "sleep disturb*" 8. "sick child*" 9. "ill child*" 10. "sick adoles*" 11. "ill adoles*" 12. 1 OR 2 OR 3 13. 4 OR 5 OR 6 OR 7 14. 8 OR 9 OR 10 OR 11 15. 12 AND 13 AND 14 Supplementary databases (Pubmed, Scopus, Web of Science): Parent* OR mother* OR father* AND "sleep quality" OR "quality of sleep" OR "sleep disrupt*" OR "sleep disturb*" AND "sick child*" OR "ill child*" OR "sick adoles*" OR "ill adoles*" was moved forward for full-text screening. Hand searches included reviewing two journals chosen based on the number of database search results, Google Scholar, and reference lists of the final articles. Full-texts on the resultant articles were read to determine if they met the inclusion criteria. Eleven articles resulted in different opinions/unsure of including and the final decision for inclusion was made by a third author.

| Phase 2: analysis phase
Data analysis of the included articles followed the six stages of Braun and Clarke's (2006) thematic analysis (familiarisation with the data, coding, generating initial themes, reviewing themes, defining and naming themes, writing up) and are incorporated throughout the phased principle-based concept analysis.

Phase 2; stage 1: initial note-taking
Each article was reviewed in-depth. Familiarising included reading the article, and notes or text were highlighted on the article itself on anything of interest. Parental sleep terms or associated terms/characteristics were highlighted on the article. Notes were made separately for each of the four principles and consisted of (1) Epistemology, if any definitions were made or part definitions about the concept, characteristics used, terms and associated terms used, (2) Pragmatic, tools and methods used to measure/explore the concept, (3) Linguistics, notes on consistency and use of terms, (4) Logical, theories mentioned around the concept. Notes were also made for the conceptual components identified in the articles that are covered in more detail in Phase 3; Stage 3.

Phase 2; stage 2: adapt and pilot test the quality criteria tool
To enhance reliability and validity, three authors (with one author also acting as facilitator) independently reviewed six articles against the quality criteria for a phased principle-based concept analysis for comparison of answers and adapting the quality criteria tool TA B L E 2 Inclusion/exclusion criteria and database results F I G U R E 1 PRISMA flow diagram of the screened studies (Appendix S1, Quality criteria) to the concept. Articles included in the pilot test covered various methods (qualitative, quantitative, mixed-methods), research conducted in different countries and disciplines to ensure a variety of research was reviewed. The articles and a spreadsheet with the quality criteria were emailed to the researchers, and the articles were split and reviewed over three online meetings. The guidelines for the pilot test involved reading each article twice, completing the quality criteria with "Yes", "Partly" or "No" (Quality Criteria scores: Yes -2 points, Partly -1 point, No -0 points) for the questions and providing evidence for the decision on the spreadsheet for comparison, and providing a score for each principle and an overall rating for the article. Before each meeting, the facilitator collated the results of the reviews, and the quality criteria spreadsheet was updated based on previous discussions and emailed to the researchers. Group discussions also enabled familiarisation of the data and reviewing the findings against the tool. Reviewing a small number of articles at each meeting enabled any queries to be covered to aid the following meetings, comparison of results, and to adapt the tool as required to the concept.

Phase 2; stage 3: quality criteria assessment
Further familiarisation occurred with rereading the article and completing the quality criteria for a phased principle-based concept analysis tool on a spreadsheet as outlined in phase 2; stage 2. This was an iterative process reviewing the article and previous notes made. Appendix S1 shows the Smith and Mörelius (2021) quality criteria tool for a phased principle-based concept analysis adapted to the concept, parental sleep when their child is sick.
Phase 2; stage 4: integrate data Braun and Clarke's (2006) stages of coding, generating initial themes, and reviewing themes are included here. Key points of the article were coded deductively in NVivo (QSR International Pty Ltd, 2018) to the principle it most closely associated with. For example, Epistemological -text was coded to definitions/part definitions, terms/characteristics used, associated terms (e.g., stress, depression). Pragmatic -if the research was useful, applicable, and appropriate to the concept, tools used to measure/explore parents' sleep (e.g., questionnaires, diaries), and recommendations.
Linguistic -consistency/inconsistency of terms. Logical -any noted or lack of boundaries with other concepts and models/theories mentioned. Coding also included references to the conceptual components, preconditions, and outcomes. The characteristics were captured and coded to the epistemological principle. During coding, the initial notes were referred to, and key and associated terms were checked off to ensure all terms were captured and acted as a validity check. The quality criteria notes for each principle were also referred to as this provided an overview of each article. Initial themes were generated inductively within each principle. Once all the articles had been coded, the initial themes were reviewed against the dataset and combined and defined. This involved critically examining the concept of parental sleep when their child is sick according to the clarity of definition (epistemology), applicability of the concept (pragmatic), consistency in use and meaning (linguistic), and differentiation of the concept from related concepts (logical) (Bicking Kinsey & Hupcey, 2013). Regular meetings were held throughout the analysis process with two of the authors to explore the data and to discuss themes. Final themes were reviewed with all the authors.

| Phase 3: results phase
The quality criteria findings, summative conclusions of the four principles, the conceptual components and the theoretical definition of parental sleep when their child is sick are presented. Braun and Clarke's (2006) fifth stage of defining and naming themes and sixth stage of writing and presenting the findings are presented in this section under each principle. When more than 10 articles are cited, this number is stated (e.g., 34 out of 56 articles) with an example reference for readability purposes. Where multiple points are presented in one sentence, a reference is provided for each point. The complete list of these references is provided in Appendix S3, Table   of references, with a point number that section refers to (e.g., see Appendix S3, Table of references, point 1). The example references have been selected based on recently published articles or to ensure various articles are cited throughout the text.

Phase 3; stage 1: quality criteria findings of the included articles
The final dataset consisted of 74 articles. Appendix S2 highlights the literature overview. Table 3 shows a visual summary of the findings (noted as a useful representation of qualitative research Smith et al., 2018)) to highlight the articles to the four principles and the quality scores of the included articles. No studies were excluded because of the scores since the purpose of this study was to define a concept.

Phase 3; stage 2: summative conclusions of the four principles
Each principle is reviewed and discussed under the following principles subthemes. Table 4 provides a summary of the principles findings.

Epistemological
The epistemological principle focuses on what is known about a concept of interest (Smith & Mörelius, 2021). The definition of a concept and whether it is clearly defined and differentiated from other con- of sleep as a basic need essential for health, well-being, and performance. The importance of sleep for recovery was also emphasised by Angelhoff et al. (2015). Commonly, measurable aspects of sleep around time were referenced, especially in terms of sleep patterns, including bedtime, sleep onset latency, night waking, morning wake time, and overall sleep quality (Meltzer et al., 2010).
Adequate sleep was defined as falling asleep within 5-10 min after the light is out, night-time total sleep time of no less than 7 h per day, staying asleep for at least 90% of the time in bed, and feeling Despite studies often omitting a definition of sleep quality (Albayrak et al., 2019;Chu & Richdale, 2009;Cottrell & Khan, 2005;Liu et al., 2021;Pouraboli et al., 2019;Yilmaz & Alemdar, 2020), it has been described as how well a person has slept, and how tired they feel upon waking . Parental sleep when their child is sick was referred to as experiencing poor sleep quality that included descriptions such as waking earlier (Mihaila & Hartley, 2016), frequent night awakenings (Yuwen et al., 2016), and less sleep (Mihaila & Hartley, 2016;Yuwen et al., 2016). Parents being supported has been shown to impact sleep quality. When parents feel supported, it has been found they perceive their sleep quality as good, despite reporting more nocturnal awakenings . E2: Is 'parental sleep when their child is sick' differentiated/distinguished from other concepts (e.g., child's sleep, controls, sleep diseases, exhaustion, depression, mood, and other biopsychosocial health)? P1: Is 'parental sleep when their child is sick' useful and applicable (e.g., researching 'parental sleep when their child is sick' and/or applies to 'parental sleep when their child is sick' through the study purpose/aims of the research/identification of knowledge gaps, findings, and recommendations) within health disciplines (e.g., beneficial to healthcare, clinical practice, or research)? P2: Has the concept 'parental sleep when their child is sick' been appropriately measured/explored and evaluated (e.g., ethical considerations, sample, measures used, policies/interventions developed)? L1: Is 'parental sleep when their child is sick' or the language, or the key attributes and characteristics around 'parental sleep when their child is sick' identified and used consistently within the whole article? L2: Is 'Concept' or the language or the key attributes and characteristics around 'parental sleep when their child is sick' used appropriately within the context of the article? LO1: Does 'parental sleep when their child is sick' hold its boundaries through theoretical integration with other related concepts (e.g., in theories, models, or frameworks)?
The overall quality scoring scale 12-14: Provides significant information to advance understanding of 'parental sleep when their child is sick'. 9-11: Provides good information to advance understanding of 'parental sleep when their child is sick'. 5-8: Provides some useful information to advance understanding of 'parental sleep when their child is sick'. 0-4: Provsides minimal information to advance understanding of 'parental sleep when their child is sick'.  (Cottrell & Khan, 2005), it was also defined as a few hours of sleep (Cottrell & Khan, 2005) and taking longer than 30 min to fall asleep   Wright et al., 2006), sleep quantity (e.g., Cheezum et al., 2013), sleep efficiency (e.g., Boergers et al., 2007), and total sleep time (e.g., Goldman et al., 2012) (see Appendix S3, Table of references, point 6). Similarly, parents of sick children were described as having inadequate (Lee & Hsu, 2012;Wright et al., 2006;Yuwen et al., 2016), insufficient (Byars et al., 2020;Moore et al., 2006), deficient (Meltzer & Booster, 2016;Meltzer et al., 2015), or restricted sleep . Earlier wake times were noted, for example, in parents of children with autism spectrum disorders (Meltzer, 2008) and ventilator dependency (Meltzer & Mindell, 2006) when at home. Later wake times were also found for parents rooming in with their children at hospital in comparison with home due to more awakenings (Meltzer et al., 2012). Some studies reported that parents caring for sick children had difficulties falling back to sleep once awoken, with others falling straight back to sleep . Some parents did not sleep if they were not near their child . These studies highlight that sleep is an individual experience that can be influenced by a range

Subjective explorations. Many studies used qualitative approaches
to explore the concept. Interviews with parents regarding their sleep experiences were conducted Angelhoff et al., 2015Angelhoff et al., , 2020Edell-Gustafsson et al., 2014;Nassery & Landgren, 2018;Neu et al., 2014;Stickland et al., 2016), and less common in combination with diaries and photos , and questionnaires . Open questions in the form of a qualitative questionnaire format varied from being used solely Stremler et al., 2011), including closed questions (Wright, 2010;Wright et al., 2006), and alongside actigraphy (Franck et al., 2014) and other questionnaires (McCann, 2008;Zupanec et al., 2010). Similar to the limitations noted with the PSQI, qualitative interviews were used alongside the Epworth Sleepiness Scale to capture sleep problems faced by parents .
Appropriateness was at times questioned. For example, some studies used a lot of questions , did not describe the analysis process or method Stickland et al., 2016), or used closed questions (Nassery & Landgren, 2018) for qualitative studies. Whereas other studies reported the credibility of the analysis Stremler et al., 2011;Wright, 2010) or justified why a particular method was used Angelhoff et al., 2015) Lee et al., 2007;Meltzer, 2008;Stremler et al., 2014;Yuwen et al., 2016). Actigraphy was also often recommended for future studies to remove biased reporting (e.g., Mihaila & Hartley, 2016) and over estimations with some studies excluding fathers entirely as it was stated that generally, mothers were the primary caregiver (Neu et al., 2014) or insufficient results from the fathers for reliable statistical analysis were received (Yılmaz et al., 2008). Many studies highlighted the need to conduct more studies with fathers (Meltzer, 2008;Meltzer & Booster, 2016;Meltzer et al., 2010;Mörelius & Hemmingsson, 2013;Yılmaz et al., 2008), especially considering they are becoming increasingly involved in the care of their children (Mörelius & Hemmingsson, 2013). Further research on single parents was also recommended to gain a complete view . In summary, the concept is recognisable in clinical practice yet still in its early stages. It is likely that no single approach currently captures the whole experience. The use of quantitative tools is significant and

Conducting longitudinal research was another recommendation
shows an application of parental sleep when their child is sick as a concept of interest to practice. The difficulty remains in the usefulness of these tools and the samples used.

Linguistic
The consistent and appropriate use of the concept was explored along with the context fit through the linguistic principle.
Variety of terms. Due to not having a specific definition, the analysis of the linguistic principle revealed that a variety of terms were used in the literature to describe parental sleep when their child is sick. Across disciplines, there was some consistency in use and the meaning of terms regardless of the population, and the contextual setting used to explore the concept. Parental sleep when their child is sick was commonly described in the epistemological principle by sleep quality, sleep disturbance, sleep patterns, sleep duration, sleep efficiency, sleep latency, to name a few. As mentioned in the pragmatic principle, quantitative research dominates the research base, with the PSQI and actigraphy being common tools used and employing many of these terms. Yet, these terms were also present in the qualitative data suggesting that implied meaning is to some extent consistent.
Overlapping descriptions. The inconsistency occurs with the overlap of some of these terms described in the epistemological principle. In summary, the implied meaning of the concept, parental sleep when their child is sick, within the literature is often inconsistent and has the potential to be interpreted differently. The variety of synonyms used and the lack of conceptual precision allows wide variation in attributed features providing a need for clarification.

Logical
The logical principle assesses whether the concept holds its boundaries when integrated with other related concepts (Penrod & Hupcey, 2005). This principle explores the theoretical integration of the concept "parental sleep when their child is sick" with related concepts.
Interrelated concepts. Psychological factors, for example, mood Similarly, cross-sectional study designs make it impossible to establish causal relationships, for example, between caregiver burden and sleep quality (Ortiz-Rubio et al., 2021) and sleep and asthma .

Differentiation. Differentiation was shown in comparisons with
parents of typically developing children. For example, Shaki et al. (2011) found mothers of children with epilepsy had a seven-fold occurrence of sleep disturbances when compared with mothers of non-epileptic children. Similarly, unlike parents of typically developing children whose sleep often improves over time as the child ages, parental sleep when their child is sick involves long-term care requirements and sleep disturbance leading to detrimental effects on parents' health (Bourke-Taylor et al., 2013). In contrast, boundaries were not maintained with parents and the child's condition. It was found that the child's condition impacted parents' sleep (Byars et al., 2020;Cadart et al., 2018;Feeley et al., 2021;Nassery & Landgren, 2018), with some arguing a reciprocal relationship (Boergers et al., 2007) where poor sleep hygiene practices implemented by parents also have a role to play and impact the child's sleep (Boergers et al., 2007;Zupanec et al., 2010).
More applied applications included Karasek, Theorell's (Karasek & Theorell, 1990) demand-control-support model , Lazarus and Folkman's (1984) theory of stress, appraisal, and coping (Feeley et al., , 2021, and the sleep-stress cycle (Mihaila & Hartley, 2016)  Similarly, Feeley et al. (2014) adapted Lazarus and Folkman (1984) theory of stress, appraisal, and coping to parental sleep and highlighted that sleep quality and caregiver burden have been shown to influence stress in maternal caregivers and may act as antecedents to the maternal caregiver's appraisal of the situation (Fletcher et al., 2008;Gallagher et al., 2009). Feeley et al. (2021 used the theory as a guiding framework for their study. Mihaila and Hartley (2016) discussed the mutual impact of stress and sleep in their cycle on the child's behaviour and the psychological well-being of the parent.
This model also covers the quantity of total sleep time and, interestingly, covers the perceived quality of sleep in maintaining healthrelated well-being (Lee, 2003;Lee & Hsu, 2012). Lee's (Lee, 2003) impaired sleep model described in the study of Lee and Hsu (2012), is more applied to the concept and suggests that sleep deprivation and sleep disruption are characterised by fragmented sleep during the night and contribute to physical and mental outcomes.
In summary, the conceptual boundaries of parental sleep when their child is sick were clear with some related concepts (parents of typically developing children) and blurred with others (e.g., stress, depression, mood, anxiety, fatigue, exhaustion, child's condition).
The concept has been applied within theoretical applications either indirectly or to some extent directly, yet there was not a specific theory/model/framework to parental sleep when their child is sick.
The concept often does not maintain its identity as its boundaries are often blurred and were not indistinguishable within theoretical applications.
The evidence reviewed supports the utility of the concept "parental sleep when their child is sick" (pragmatic principle). However, there is a lack of a precise definition of the concept with a reliance on implied meaning (epistemological principle), which has led to the use of the concept being inconsistent (linguistic principle), and frequently blurred when theoretically positioned with other concepts (logical principle).

Phase 3; stage 3: conceptual components
Informed by the findings from each principle and additional notes and coding made to the three aspects of the conceptual components, the conceptual components of parental sleep when their child is sick are now organised into preconditions (phenomena/events that precede an instance and that influences the concept), characteristics (frequent words or expressions used to describe the experience of the concept), and outcomes (the consequences that follow the occurrence of the concept) (Waldon, 2018). These conceptual insights assist in advancing clarity and understanding of the concept and contribute to the theoretical definition, the final product of the principle-based concept analysis. Figure 2 shows the conceptual model of parental sleep when their child is sick and the interactions between the components.

Preconditions
The child's condition was the primary precondition which has been shown to involve parents adjusting their sleep patterns, attending to their child more during the night, and may result in parents accepting their sleep loss Heaton et al., 2006). The impact can further be heightened by family, friends, and healthcare professionals normalising the lack of sleep for parents and not seeking help . Other features linked to the child's condition include psychological factors including stress, anxiety, worry, for example, in obtaining a diagnosis.
Context, in terms of the sleeping environment such as staying with their hospitalised child, can influence parents' sleep, the accommodation provided, and whether parents have their own room or share the room with others .

Characteristics
Factors suggested as characteristics of parental sleep when their child is sick included poor sleep quality, prolonged sleep latency, frequent sleep disturbance, and shorter sleep duration. What coping strategies and support parents have in place also influences the concept. For example, coping was linked to parents practising yoga (Neu et al., 2014), meditation (Neu et al., 2014;Stremler et al., 2011) and exercise , spirituality and faith  and found to help parents to practise better sleep. Support included the family, healthcare professionals/nursing support/home support/care plans , information support on the condition Feeley et al., 2014;Larson et al., 2012;McCann, 2008), and sleep hygiene to improve sleep (Cottrell & Khan, 2005;McLoone et al., 2013;Shaki et al., 2011;Stremler et al., 2014;Yuwen et al., 2016;Zupanec et al., 2010).

Outcomes
The consequences of sleep are focused on biopsychosocial factors.
Biologically, cardiovascular disease (Angelhoff, Askenteg, et al., ents experienced a lack of energy to engage in activities and social events . Parents were reported to miss their social life with friends and relatives (Edell-Gustafsson et al., 2014). Sleep disruption was associated with tiredness and limiting the parents' ability to work and socialise . Social support was also found to be associated with longer sleep .

Phase 3; stage 4: theoretical definition
The theoretical definition is presented based on the findings of the principle-based concept analysis, including implied meanings and the conceptual components. The following theoretical definition is

| Strengths and limitations
The strengths of this analysis included each article being read twice, and a pilot test with a selection of articles was undertaken with three researchers aiding reliability and validity of the analysis.
Consultation of the findings was reviewed by a varied research team.
Only English language articles were included, which may potentially limit the findings. A small number of studies included did not use val-
The findings from this study highlight the need to develop a tool for parental sleep when their child is sick.

| CON CLUS IONS
This phased principle-based concept analysis provided a rigorous evaluation of parental sleep when their child is sick using a triangulation of methods. The results of this analysis have shown many gaps in our understanding of this concept, resulting in a lack of clarity, consistency, and definition. This concept analysis is a starting point for concept advancement. The results of this study have pragmatic implications for scientific inquiry and clinical practice. How we define parental sleep when a child is sick impacts how it is studied and how interventions are planned. This concept analysis and theoretical definition serve as a basis for future research, particularly in further clarity of this concept.

ACK N OWLED G EM ENTS
We would like to thank Lisa Webb, Librarian, at Edith Cowan