# Considering the Consequences of Cybersickness in
## 1 Introduction  
Virtual reality (VR) is a rapidly advancing technology that provides an immersive and interactive digital environment for users to experience computer-generated simulations in a realistic and engaging way. This technology has been developing rapidly in recent years and holds significant potential for various applications, including entertainment, healthcare, education, and business [1, 2]. Among these topics, using VR for healthcare has been attracting increasing attention in recent years. Rehabilitation is crucial in clinical and healthcare scenarios as it enables individuals to regain independence, enhance their quality of life, and reach their full potential in daily activities. Conceptually, rehabilitation is a multifaceted process that aims to restore physical, psychological, and social functioning after a period of illness, injury, or addiction. It takes into account the intricate interplay among biological, psychological, and social factors that may affect a person's capacity to function and achieve their goals. Ultimately, rehabilitationis a process that considers the whole person and their unique circumstances to support them in their journey towards optimal health and well-being. Manual rehabilitation is deficient in providing consistent and personalized feedback and monitoring. From the user perspective, patients with less motivation and satisfaction mostly result in obsolete applications [3]. What is more, the characteristics of patients may even determine the degree of recovery from physical or physiological sickness [4]. Against this background, many new technologies are seen to be viable options for investigating the possibilities of high-efficiency approaches. In 2003, Burdea classified virtual reality therapies for rehabilitation as virtual rehabilitation [5]. Since then, virtual rehabilitation has been a significant topic in medical care for the past 20 years. Formally, virtual rehabilitation is a modern approach that utilizes virtual reality technology to deliver therapy, assessment, and training to individuals with various physical and mental conditions. The goal of virtual rehabilitation is to enhance the traditional rehabilitation process by providing an immersive, interactive, and engaging experience that can promote motor and cognitive skills, improve functional outcomes, and enhance the overall quality of life [6; 7]. Studying immersive virtual rehabilitation can advance our understanding of the effectiveness and optimal implementation of this novel technology for improving rehabilitation outcomes, particularly in populations with limited access to traditional rehabilitation methods. Virtual rehabilitation can be divided into different categories based on the types of conditions it aims to address: cognitive impairment, acquired brain damage, and physical inactivity [8; 9; 10]. Firstly, cognitive impairment might lead to dementia or apathy. This illness exists with memory, language, and judgment issues that are not severe enough for patients to interfere with daily activities [11]. Different from cognitive impairment, acquired brain injuries might be related to head trauma and increase the risk of neural connection problems. Specific symptoms of brain injuries include stroke or Parkinson's in patients who lack the capacity to care for themselves in daily life [12]. Finally, physical inactivity is more common, and virtual rehabilitation may aid in patients recovering from physical injuries or increase exercise cognitive abilities [13]. Cybersickness is a phenomenon that arises from exposure to immersive virtual environments, causing a range of symptoms, such as nausea, ocolomotor, and disorientation. It is a common challenge in VR applications, and its severity can be influenced by several factors. Understanding the underlying mechanisms and factors that contribute to cybersickness is crucial for the development of effective interventions to reduce its impact on users' experience and promote the safe use of VR technology, especially under virtual rehabilitation scenarios.