Impact of health behaviours on physical health: Research on over 20,000 participants analysed the impact of four key positive health behaviours on mortality risk - non-smoking, physical activity, consumption of less than 14 units of alcohol per week and a diet rich in fruit and vegetables. Participants who adopted all four health behaviours at baseline had a mortality risk that was equivalent to being 14-years younger at follow-up (average of 11-years later), compared to those who adopted none of the positive health behaviours
(Khaw et al., 2008). behaviours
(Khaw et al., 2008). A more recent study focused on six health behaviours: non-smoking, physical activity, healthy diet, sleeping 7 to 8 hours a night, inactivity less than 8 hours a day, and daily social contact
(Martínez-Gómez et al., 2013)(Martínez-Gómez et al., 2013). Results again highlighted a mortality risk that was equivalent to being 14-years younger for those who adopted these behaviours relative to those who adopted none.
Wen et al. (2011) conducted a prospective cohort study with over 400,000 individuals between 1996-2008. Surprisingly, even those individuals in a low physical activity group (average of 15 mins a day or 92 mins per week) had a 14% reduced risk of all-cause mortality. Moreover, every additional 15 minutes of daily exercise beyond this minimum amount, reduced all-cause mortality by a further 4%. The authors argued that less exercise is easier to achieve for those who do not engage in any physical activity at all, and yet it may still be sufficient to achieve health benefits. Moreover,
Lee, Pate, Lavie, Sui, Church, and Blair (2014) concluded that running 5-10 minutes a day at slow speeds (less than 6mph) is even associated with reduced all-cause risk of mortality, providing further evidence that exercising below current minimum guidelines is sufficient for mortality benefit. Once a routine is established individuals may then be able to be motivated to exercise at higher levels.
The relationship between diet and physical health has also been widely reported. For example, the vegetarian diet has been associated with a reduced risk for disease development, including coronary heart disease and type 2 diabetes, compared with a diet containing red and processed meat
(McEvoy, Temple, and Woodside, 2012), while insufficient fibre has been associated with colon cancer, high blood cholesterol, diabetes, coronary heart disease and obesity
(Jefferson and Cowbrough, 2005). Diet is also associated with all-cause mortality, with one study on a sample of 2000 individuals, finding that those adhering to a Mediterranean diet had an all-cause mortality risk that was 34% lower than those who did not
(Limongi et al., 2017).
With regards to sleep,
Watson et al. (2015) concluded that 7 hours or more sleep per night produces optimal health in adults. Sleeping less than 7 hours a night is associated with obesity diabetes, hypertension, heart disease, stroke, depression and increased mortality. Moreover, a recent prospective twin study
(Åkerstedt 2017) found that both short (defined as <6.5 hours) and long (defined as ≥9.5 hours) sleep were linked to increased mortality. However, it is important to note that these statistics are generalisations, with small groups of people fully able to function healthily on shorter periods of sleep such as those with a mutation in the DEC2 gene
(Pellegrino et al., 2014; He et al., 2009).
Impact of health behaviours on physical and mental health: Being physically active is also associated with improved mental health
(Penedo et al., 2005; Chekroud et al., 2018), with NICE guidelines now recommending physical activity for people with mild depression. Increasing physical activity reduces risk of all-cause mortality as well as disease specific death including cancer, cardiovascular disease, diabetes, hypertension, depression and osteoporosis
(Parkin, 2011; Warburton et al., 2006; Boyne et al., 2018). . Exercise has also been show to lead to improvements in self-esteem
(Barton and Pretty, 2010), vagal function
(Reference), and even neuroplasticity
(Kandola et al., 2016).
Diet is also associated with mental health, with a healthier diet predicting better mental health and wellbeing
(Dimov et al., 2019; Kulkarni et al., 2015; Emerson et al., 2019; Rooney et al., 2013). Focusing on whole diets, the Mediterranean diet has proven useful in slowing age-related deterioration, including improvements in cognitive function and reducing risk of cognitive impairment and dementia
(Petersson 2016, Aridi 2017), with B-vitamins and antioxidants playing a key role
(Moore et al., 2018; Castelli et al., 2018). The Mediterranean diet has also proven effective in reducing depression symptomology (according to an RCT)
(Parletta et al., 2019). Based on the evidence, dietary recommendations for the prevention of depression have been proposed; adopting "traditional" diets, such as the Mediterranean diet, increasing consumption of fruits, vegetables, legumes, wholegrain cereals, nuts, seeds, foods rich in omega-3 polyunsaturated fatty acids and limit consumption of processed foods
(Opie et al., 2017). We note here that socio-structural factors (e.g. poverty) will impact on individuals capacity to follow such advice.
Poor sleep is also associated with common mental disorders, while improving sleep in these patients can lead to mental health improvements
(Freeman et al., 2017). Analyses on nearly 100,000 adolescents in Japan found a U-shaped association between mental health status and sleep duration
(Kaneita et al., 2007). The authors also reported a positive correlation between mental health status and subjective sleep assessment. Similarly, among an elderly population, sleep problems were associated with worsened mental and physical health-related quality of life
(Reid et al., 2006).
In a study on over 4500 adolescents, health behaviours were measured across several domains; diet, specifically consumption of carbonated soft drinks and fast food, tobacco use and physical activity. Participants were then allocated a number ranging from zero to "four or more" depending on the number of unhealthy behaviours they engaged in
(Rao et al., 2015). Results highlighted that participants with a score of four or more were significantly more likely to be anxious, experience suicidal ideation and have been involved in a physical fight, compared to those who scored zero. Analysis of over 2400 Chinese college students found those who frequently consumed alcohol, had disturbed sleep, poor dietary behaviour and internet addiction disorder. This was associated with significant increased risk of depression and anxiety
(Ye et al., 2016).
Summary
INTEGRATE PARAGRAPH PARAGRAPH ON VAGAL FUNCTION AND EMPHASISE THAT BOTH BOTH CHANGE IN VAGAL FUNCTION: As with physical activity and diet, changes in sleep are associated with changes in vagal function, such that reduced vagal function (combined baseline and reactivity measures) is associated with sleep disruption (El-Sheikh, Erath, and Bagley, 2013). Intriguingly, increases in resting state vagal function have been shown to predict better subjective and objective sleep quality (Werner et al., 2015; Grimaldi et al., 2016). By contrast, reduced HRV (as measured over a 24-hour period) has also been detected early during early stages of sleep-related breathing disorders (Aeschbacher et al., 2016). INTEGRATE: For instance, scholars have emphasised for example, that community resilience is underpinned by the individuals within it, highlighting the role of a positive outlook and individual strengths, which underpin a community's capacity for resilience and agency \cite{Berkes_2013}.
Focus on Community
Here we focus on the relevance of community to individual wellbeing, a major focus of our original GENIAL model \cite{Kemp_2017}. The Japanese have a word to describe "lonely death" - ‘kodokushi’ - which refers to people dying without friends or family, and sometimes these individuals are not found for many weeks... or months. ("Dead people don't pay their bills"). Tragically, these experiences characterise the modern world, and especially individualistic cultures. Social ties are deteriorating and loneliness is on the rise \cite{Kushlev_2017,Twenge_2013,twenge2014,putnam2001}, the reasons for which are complicated, but may involve a host of interconnected societal issues including generational shifts in narcissism \cite{Twenge_2013,twenge2014}, increasing individualism (versus collectivism) in western society \cite{Heu_2018,Brewer_2007}, and inequality \cite{Scheffer_2017,scheidel2017,r2010}. Critically, loneliness has important impacts on health and wellbeing. For instance, a meta-analysis of studies on more than 300,000 participants reported that a lack of social ties are associated with a 50% increased risk of premature mortality over a 7.5 year follow-up period, an effect that was stronger than physical activity, smoking (15 cigarettes daily) and body mass index \cite{Holt_Lunstad_2010}. In a more recent study on 48,673 participants, the same researchers \citep*{Holt-Lunstad2015} observed that social isolation (29%), loneliness (26%), and living alone (32%) increase risk for premature mortality, reporting no differences for objective and subjective measures. Furthermore, greater impacts on mortality were observed among those under the age of 65 years.
Social isolation and loneliness may lead to ill-being via a host of behavioural, psychological and physiological factors. Associated behavioural factors include physical inactivity and smoking \cite{Shankar_2011}, substance use and hazardous drinking \citep*{Stickley2014}, while psychological factors include decreases in self-esteem, increased risk of depression, and feelings of hopelessness \citep*{Steptoe_2004}, contributing to a dysregulation of cardiovascular, metabolic, and neuroendocrine processes \citep*{Grant2009}, higher systolic blood pressure, independent of several factors such as age, gender, cardiovascular risk factors, medications, social support and perceived stress \citep*{Hawkley_2010}. The NIACT \cite{Kemp_2017a} and GENIAL \cite{Kemp_2017} models integrate these behavioural, psychological and physiological factors into an innovative framework within which pathways to health and ill-health may be understood, bridging the gap between psychological moments and mortality.
Further to our original GENIAL model \citep{Kemp_2017}, the relationship between social ties and health was recently comprehensively reviewed in a book titled 'The New Psychology of Health: Unlocking the Social Cure' \citep{2018}. Social identity theory helped to contextualise the research that was discussed, emphasising that people conform to the norms of the group to which they identify. Therefore, the actions and thoughts of the group become the reference point for the individual. If an individual's perception of others in a representative group is positive, individuals of that group will think and behave similarly. Peer modelling has proven to be an effective intervention to increase fruit and vegetable intake \cite{Horne_2008}, although only when modelled by someone that shares the same group identity \cite{Cruwys_2012}. By contrast, if an individual was to identify with a group whose health behaviours are risky, they are more likely to participate in negative health behaviours. Research has shown there is a relationship between strength of group identification and smoking status when smoking is a normal group behaviour \citep{Schofffild_2001}. Intriguingly however, the more group identities an individual has, the less likely they are to engage in negative health behaviours, such as cigarette smoking, alcohol consumption, and use of illicit drugs \citep{Miller_2016}.
Social identity theory provides a useful context within which to understand the influence of community on the health and wellbeing of the individual; within which are several theories providing explanations as to how a social identity can serve to protect or enhance health and wellbeing \citep{Haslam_2008}. For example, social identity provides meaning, purpose and worth to an individuals life (the meaning hypothesis) \cite{de_Vroome_2013,Nakamura_2013,Peterson_2005}, the importance of which is highlighted previously as part of positive psychological experiences \cite{Alimujiang_2019}. Social identities also facilitate the extent to which others are likely to provide social support (the support hypothesis) \cite{Cohen_2004,Levine_2002,Levine_2005,Platow_2006}, and provide a sense of efficacy, agency and power to an individual (the agency hypothesis), contributing to the sense that 'the whole is greater than the sum of its parts' \cite{Haslam_2018}. Strikingly, research has demonstrated that cardiac and respiratory patterns synchronise when members of a choir sing in unison, compared to when singing independently \citep*{Timmons2015}. This phenomenon of 'physiological linkage' may help to explain both reduced relationship satisfaction and increased relationship connectedness \citep{Timmons2015}. For example, linkage in cortisol levels is associated with worsened relationship satisfaction, but linkage among multiple systems is associated with increased relationship connectedness.
To conclude, community is important for individual health and wellbeing as it provides the environment in which individual health and wellbeing may be achieved. A supportive community will therefore contribute to the health and wellbeing of individuals within that community, and this relationship will be a bidirectional one such that improved health and wellbeing of individuals will also foster community wellbeing. Community resilience is a social-ecological system, nested within different levels of a complex system - the 'symbioment' (see fig \ref{881013}) - which is (perhaps over-) simplified in the present paper to levels that include the individual, community and the environment. We now turn our attention to the wider environment in which individuals live and work, focusing on a major societal challenge to human health and wellbeing: anthropogenic climate change.
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INTEGRATE: Further to this, research has demonstrated that culture can moderate the influence of positive emotion, highlighting an important role of culture when considering the influence of emotions. Among Western cultures, positive feelings are associated with individual success, high self-esteem, and good health \citep{Heine_1999,Kitayama_2000,Taylor_1988}. Whereas in Japan, for example, they are more likely to associate happiness with negative social consequences, such as jealousy and disharmony among relationships \citep*{Uchida_2004}. Another reason which may contribute to this cultural difference is that Asian cultures seek to achieve a balance between positive and negative affect, whereas Western cultures place importance on maximising positive affect, while minimising negative affect \citep*{Leu_2011}.