Introduction

The International Council of Nurses, through the International Classification of Nursing Practice, defines the concept of sleep as a bodily process, which refers to the "recurrent decrease in bodily activity, marked by reduced consciousness, not being awake, accompanied by inattention, with decreased metabolism, immobile posture, decreased physical activity and decreased sensitivity to external stimuli, but readily reversible" (^{Classificação Internacional para a Prática de Enfermagem, 2019}).

Sleep is a basic physiological function, and well-being and quality of life depend on the quantity and quality of sleep (^{Mercadante et al., 2017}). The onset and maintenance of the sleep process depends essentially on the suppression of activity in the ascending conduction systems, a process that is realised through the inhibition of neurons in the preoptic area, located in the lateral region of the cerebral ventricles. It is characterised by a period in which there is a loss of consciousness and, generally, a frank decrease or absence of bodily activity, in which the person remains with their eyes closed. Sleep, from its beginning to its end, is not a homogeneous process and essentially consists of two phases: the rapid eye movement (REM) phase, which is associated with active dreams, and the non-rapid eye movement (NREM) phase, where there is a significant reduction in skeletal muscle tone, which progresses to partial or complete atonia. Generally, the sleep sequence is cyclical, with periods of REM and NREM sleep alternating every 60 to 90 minutes (^{Carley & Farabi, 2016}).

Among the many existing sleep disorders, the most prevalent in palliative care (PC) are insomnia and hypersomnia (^{Monteiro et al., 2017}).

Insomnia is a heterogeneous complaint that can involve difficulty falling asleep (initial insomnia), difficulty maintaining the sleep cycle, characterised by frequent nocturnal awakenings (intermediate insomnia), inability to resume sleep after awakenings at the end of the night (terminal insomnia) or complaints that the sleep period was not restorative (^{Savard & Morin, 2001}).

On the other hand, hypersomnia refers to the complaint of excessive and disabling daytime sleepiness. In this situation, patients find it difficult to remain alert during the main waking hours of the day, falling asleep unintentionally and at inappropriate times that interfere with their daily routine (^{Karna & Gupta, 2021}).

Sleep disorders are a challenge in the context of PC, not only for the patients themselves but also for their families. Disturbances in this spectrum add a load of stress to the worries already inherent in managing an advanced, incurable and progressive disease. In palliative care patients, daytime activity is usually reduced, leading to a lack of definition in the sleep-wake cycle, especially when the daily routine involves long periods confined to bed. Mental agitation and restlessness at night can result in long periods without rest, which contribute to the development of problems related to the sleep cycle (^{Hajjar, 2008}). In this context, insomnia is generally assumed to be an effect of other comorbidities, associated with depressive or anxiety disorders, assuming that it will be resolved with the treatment of these conditions. However, this assumption is erroneous and the lack of treatment for sleep-related disorders can contribute to an increase in the stress burden, which in turn can lead to the actual worsening of symptoms associated with these conditions (^{Mercadante et al., 2015}).

Sleep patterns can be improved through the implementation of pharmacological and non-pharmacological interventions. However, the current existence of a wide range of targeted pharmacological therapies and their ease of application tends to neglect the implementation of non-pharmacological therapies.

As non-pharmacological interventions to promote the quality of sleep patterns, the evidence points to the possibility of teaching, instructing and applying the basic principles of sleep hygiene to patients with palliative needs, at the beginning of their illness course. On the other hand, cognitive and behavioural interventions have shown great promise in improving symptoms related to these disorders (^{Hajjar, 2008}).

Considering the above, this Scoping Review aims to map and synthesise the evidence of autonomous nursing interventions to improve the quality of sleep patterns in patients undergoing PC, gathering information on existing interventions. The aim is to answer the following research question: Are there autonomous nursing interventions to improve the quality of sleep patterns in patients undergoing PC?

1. Methods

Generally, a scoping review is conducted with the aim of exploring or deepening the literature, mapping and summarising the existing evidence on a particular subject and identifying gaps in knowledge (^{Peters et al., 2020}). A rigorous methodological protocol must be adopted to fulfil this objective (Peters et al., 2020).

The methodological framework of ^{Arksey et al. (2005}) recommends five stages for carrying out a scoping review, namely identifying a research question; identifying relevant studies in the research area; selecting the studies to be included; mapping the data collected and, finally, collecting, synthesising and presenting the results.

Since the aim of this methodology is not to find the best scientific evidence, but rather to map and synthesise existing scientific evidence, it does not aim to analyse the methodological limitations or risk of bias in the evidence of the included studies (^{Peters et al., 2020}).

Its systematisation is based on the Joanna Briggs Institute framework, which uses the PCC mnemonic (population, concept, context) of the study to be carried out (^{Peters et al., 2020}).

In this study, the population analysed is adult patients with alterations in the quality of their sleep pattern. The concept being analysed focuses on autonomous nursing interventions to improve the quality of sleep patterns in the context of CP. No distinction was made between patients who were hospitalised and those who remained at home.

Using PCC, it was possible to develop the research question: "Are there autonomous nursing interventions to improve the quality of the sleep pattern of patients undergoing PC?".

A clear research question should contain the elements identified in the PCC, which will influence the creation of specific inclusion criteria that facilitate the research process and provide a starting point for the development of the scoping review (^{Peters et al., 2020}). In accordance with the question developed for the present research, this review included studies involving an adult population aged over 18 in need of PC and studies describing non-pharmacological interventions aimed at improving the quality of sleep patterns in patients with sleep disorders. We chose to include only primary studies (qualitative, quantitative or mixed). All studies involving paediatric and neonatal populations and interventions involving the administration of any type of drug aimed at improving the quality of patients' sleep patterns were excluded.

2. Results

The results obtained after the screening process described above are presented according to the PRISMA Extension for Scoping Reviews. The flowchart shown in Figure 1 is intended to graphically represent the number of studies identified, included and excluded, as well as the reasons for exclusions (^{Tricco et al., 2018}).

Figure 1 PRISMA flowchart of the study selection process (adapted from ^{Tricco et al., 2018}) 

The search identified 87 studies from the aforementioned databases. After removing duplicates, a total of 85 studies were identified. Of this number, after reading the title and abstract of the studies, 67 were excluded. Of the remaining 18 studies, after reading the full text, 13 could be excluded as they did not meet the predefined inclusion criteria, ending up with a total of five studies included in this review.

The five eligible studies were fully analysed and the data that answers the research question and objective of this scoping review was extracted and synthesised from them. The following table (Table 2) summarises the data resulting from the analysis of the studies, in terms of authors, year and country of origin, study objective, method, participants, interventions and results.

3. Discussion

This scoping review aims to map and synthesise the available scientific evidence on autonomous nursing interventions to improve the quality of sleep patterns in patients undergoing PC. To achieve the proposed objective, five primary studies were included, with publication dates of 2005, 2012, 2018, 2020 and 2021, which allowed us to infer that the topic has been emphasised over the years. The articles selected are representative of a total of 258 patients who received PC from three different continents (Europe, America and Asia). This reinforces the relevance of this topic and its transversality to different cultures and societies. One study reports on the reality experienced in the United Kingdom, two studies were carried out in Turkey and two in Canada.

All the studies adopted a quantitative approach. In the case of the participants in this review, in two studies they were at home and were cancer patients (^{Sela et al., 2005}; ^{Bernatchez et al., 2018}). In the other three studies, they were hospitalised (^{Plaskota et al., 2012}; ^{Yildirim et al., 2020}; ^{Aslan & Çetinkaya, 2021}).

With regard to sample size, two studies had a sample of less than 15 participants and the remaining studies had a sample of between 60 and 100 participants.

In relation to the objective of the studies in the sample, it should be noted that ^{Sela et al. (2005}) sought to describe patterns of sleep disorders and possible treatments, while the remaining studies sought to determine the effect of a specific non-pharmacological intervention in the treatment of sleep disorders. The non-pharmacological interventions addressed are cognitive-behavioural and environmental intervention (^{Bernatchez et al., 2018}), hypnotherapy (^{Plaskota et al., 2012}), the use of lavender oil (^{Yildirim et al., 2020}) and therapeutic touch (^{Aslan & Çetinkaya, 2021}).

Non-pharmacological interventions are non-invasive, science-based interventions aimed at preventing, treating or curing a health problem (^{Plateforme CEPS, 2017}). They take the form of a product, a method, a programme or a service whose content must be known by the user. They are linked to identified biological mechanisms and/or psychological processes and are the subject of efficacy studies. They have an observable impact on health, quality of life, behavioural and socio-economic indicators. Their implementation requires relational, communicational and ethical skills (^{Plateforme CEPS, 2017}).

The results of the study by ^{Sela et al. (2005}) show that sleep disorders are highly frequent in cancer patients undergoing PC. ^{Yildirim et al. (2020}) corroborate this statement, adding that the quality of life of PC patients suffering from sleep disorders is compromised.

In their study, ^{Sela et al. (2005}) reported that 53% of patients identified strategies they had tried to solve sleep problems and 44% reported using more than one sleep induction/maintenance technique. The most commonly reported non-pharmacological strategies were relaxation, visualisation and prayer.

Furthermore, ^{Sela et al. (2005}) agree that, according to the effectiveness attributed to non-pharmacological interventions, patients should be encouraged to put them into practice, referring to them as adjuncts to pharmacological therapies. The authors refer specifically to relaxation techniques, visualisation, changing positions and reading.

Through their study, ^{Plaskota et al. (2012}) prove that hypnotherapy can improve sleep in palliative patients. However, the results are controversial, as they are validated by the VSH sleep scale, but not by actigraphy. It should also be noted that the results were only perceived by the patients after the fourth hypnotherapy session.

The study by ^{Bernatchez et al. (2018}) concludes that behavioural strategies, including the control of external stimuli, are very useful from the participants' perspective. These strategies require participants to be as active as possible during the day, carrying out activities that take into account their limitations, such as cooking or writing in a diary.

^{Monteiro et al. (2017}) highlight psychological and behavioural therapies as a non-pharmacological treatment for sleep disorders, along with sleep hygiene and the correction of reversible factors.

The CBT-E (Cognitive-Behavioural and Environmental Intervention) used by ^{Bernatchez et al. (2018}) proved to be more useful for improving insomnia as the only symptom present, rather than treating hypersomnia or when these were present concomitantly. However, the authors suggest that when both insomnia and hypersomnia are present, improving one of these conditions can cause the other to worsen.

^{Yildirim et al. (2020}) agree that the use of lavender oil is an effective method for improving the overall quality of sleep in PC patients, as they found several gains when comparing the experimental group with the control group, namely the frequency of awakening, greater ease of falling asleep, deeper and better quality sleep, fewer nocturnal awakenings and better ability to fall asleep again afterwards.

The study by ^{Aslan and Çetinkaya (2021}) emphasises therapeutic touch, stating that it has a positive effect on patients' sleep quality. It is described as a non-invasive intervention used to improve sleep quality, and nurses can play a crucial role in its development and implementation.

Although the aforementioned studies show that there are several non-pharmacological strategies that can help improve the sleep pattern of patients undergoing PC, ^{Sela et al. (2005}) conclude that this symptom is neglected by the patients themselves, who tend not to report it; for this reason, the authors recommend that patients should be frequently questioned about the quality of their sleep.

It is therefore crucial for nurses to be able to intervene in this area, collecting data on the patient's sleep pattern, so that they can make decisions within the scope of autonomous nursing interventions, based on the most up-to-date evidence. Article 9(2) of the Nursing Professional Practice Regulations (^{Decreto-Lei - Decree-Law 161/96, p. 2961}) states that "autonomous actions are those carried out by nurses, under their sole and exclusive initiative and responsibility, in accordance with their professional qualifications, whether in the provision of care, management, teaching, training or counselling, with contributions to nursing research". This includes non-pharmacological interventions, which can play a major role in improving the quality of sleep of patients undergoing PC.

Conclusion

Most of the authors of the studies analysed support sleep disorders as a problem that should be seriously considered in the context of PC.

In response to the aim of this review, it can be concluded that all the studies analysed identify non-pharmacological strategies that can be autonomous nursing interventions and that aim to improve the quality of the sleep pattern of patients undergoing PC.

Although the strategies applied were different, all the authors demonstrated an effective improvement in the quality of the participants' sleep patterns after implementing them.

This review made it possible to realise that the subject is relatively recent and has been highlighted in recent years.

Author contributions

Conceptualization, D.S., A.C. and A.S.; data curation, D.S., A.C. and A.S.; formal analysis, D.S., A.C. and A.S.; investigation, D.S., A.C. and A.S.; methodology, D.S., A.C. and A.S.; project administration, D.S., A.C. and A.S.; resources, D.S., A.C. and A.S.; software, .S., A.C. and A.S.; supervision, D.S., A.C. and A.S.; validation, D.S., A.C. and A.S.; visualization, D.S., A.C. and A.S.; writing-original draft, D.S., A.C. and A.S.; writing-review and editing, D.S., A.C. and A.S.

Conflicts of interest

The authors declare no conflict of interest.