We included all articles that discussed lifestyle factors in the general population within the COVID-19 pandemic context. The review focused on the six lifestyle factors included in the definition of a healthy lifestyle by the American College of Lifestyle Medicine.

Articles were excluded if they did not focus specifically on the six lifestyle factors (dietary habits, physical activity, sleep, tobacco or other substance use, stress, and emotional well-being and social connectedness) or did not discuss lifestyle within the COVID-19 context. We excluded articles that discussed lifestyle change in healthcare workers as they are a specialized group and subject to additional stressors (long work hours, use of personal protective equipment, high risk of contracting COVID-19, dealing with deaths, constant pressure of new admissions, lack of adequate ventilators etc.) beyond the effects of the lockdown measures. Additionally, we excluded published literature reporting modeled effects of lockdown during COVID-19.

Identified articles meeting the inclusion criteria were imported into Endnote X9 ⁸ . Thereafter, the authors screened the title and abstract of the identified articles. Full texts of all relevant articles were further screened for useful data to be eventually included in the critical interpretive synthesis ⁹ . From each article, qualitative and quantitative information on the COVID-19-related lockdown and its effects on any of the six lifestyle factors (diet, physical activity, stress, connectedness, sleep, and tobacco or other substance use) on healthy individuals and those with pre-existing NCDs were extracted. In articles that were primary studies with quantitative data, we specifically scrutinized the study design, results, and the conclusion. In articles other than primary studies, we focused on the discussion and conclusion sections. For qualitative studies, opinions/perspectives, and viewpoints, we took a meta ethnographic approach ¹⁰ as part of our interpretative synthesis. Though the ACLM definition combines smoking, alcohol, and substance use as one lifestyle factor, we reviewed these separately to explore them in greater depth. The information extracted from the articles was classified according to the six lifestyle factors and is summarized in the Results.

Most of the literature included in the narrative review referring to dietary habits indicated an alteration in the eating behavior of people in many parts of the world during the COVID-19 pandemic ^{12, 13} . Most survey-based studies reported an increase in the intake of unhealthy foods by the majority of respondents, a small number highlighted a higher intake of healthy foods, and some studies, such as one from Spain with 1036 participants, reported a wide variation in the type of food (healthy vs unhealthy) consumed by the participants ¹⁴ . In richer households, staying home encouraged excessive use of unhealthy foods, such as processed and fast foods in many parts of the world ^{15– 18} . An Italian study reported an increased uptake of ‘comfort foods’ including chocolates and ice-creams used by participants to allay lockdown anxiety ¹⁵ . In a study of 938 French adults during the lockdown, an individual’s mood was a significant factor for food choice ¹⁸ . Similarly, a high prevalence of ‘emotional eating’ was reported in Saudi Arabian women ¹⁹ and among a cohort of 675 Spanish individuals ²⁰ . Additionally, some people including children had inclined towards snacking to overcome boredom ²¹ ,

Staying home also limited access to fresh vegetables and fruits, particularly in the most vulnerable and poorest sections of the society due to limited availability, accessibility, and affordability ^{22, 23} . Poorer households were overwhelmed by food insecurity, as demonstrated by a study from Iran reporting 61% of 392 families having faced some level of food insecurity ²⁴ .

In some situations staying at home encouraged many individuals to eat a fresh, home-made, balanced diet ²⁵ , as evidenced by a reduction in the consumption of fast food ²⁶ , fewer purchases of ready-made meals, and by the dominance of online/in-person grocery shopping as the major source of food and food purchases in some countries ^{27, 28} . A study from China showed that families that did online shopping included a greater variety of foods in their diet than in normal circumstances ²⁸ . A large study of 7514 participants from Spain—predominantly young, university-educated females—reported a higher intake of fruits, vegetables, or legumes than during the pre-pandemic times ²⁹ . Gender (females faring better), family members staying at home, (less) TV watching while eating, and (higher) maternal education were determined to be factors influencing healthy food intake ³⁰ .

The change in dietary habits during the lockdown period had consequences. One Polish study with 2381 participants reported that 34% of respondents ate more during the lockdown ³¹ , while another study from the same country with 1097 participants reported that 30% gained weight during the lockdown ³² . Meanwhile, among 3533 respondents from Italy, 46.1% reported consuming more food and 19.5% had gained weight ¹⁵ . A similar proportion (46%) of the Galician population from Spain also reported eating more than before the lockdown and 44% of the 1350 adults in the study reported weight gain ²⁷ . A qualitative study from Ghana found similar eating behavior leading to weight gain during the lockdown ³³ . This weight gain was more pronounced in people with pre-existing overweight/obesity ³⁴ . Boredom snacking had led to relatively quick excessive weight gain among children ^{15, 21, 27, 35– 37} . A Chinese retrospective study of 10,000 studentsalso found an increase in body mass index in most of the participants ²² .

In the review, we find that individuals who were overweight/obese pre-pandemic gained more weight during the pandemic, while the undernourished lost more weight ^{15, 32} . A study in Italy of 88 families found that children with obesity found it difficult to practice a healthy lifestyle during the pandemic, despite participating in a food education program in a hospital. Their unhealthy food consumption and sedentary lifestyle were attributed to a great deal of stress experienced by the children due to interruption of school and sports activities among other factors ³⁸ . Studies also reported that individuals with eating disorders and other psychiatric disorders diagnosed prior to the lockdown fared worse during the lockdown period due to low self-directedness and less adaptive coping ^{17, 39– 44}

The lockdown period saw a general reduction in physical activity levels as evidenced from the studies included in the review. A study from China of 339 participants revealed a significant reduction in the average exercise intensity for both males and females during the lockdown period (average steps per day, before vs during: 7038±1923 vs 3741±1042 steps, p < 0.001 for females and 8321±3000 vs 3728±1726 step, p < 0.001 for males) ⁴¹ . A similar observation was made in Italy where 68% of participants in a study with a sample size of 490 adults reported a decrease in exercise levels ⁴² . In a Polish study sample of 238, 43% of participants also reported a reduction in their physical activity during the lockdown period ³² . An international, multi-country online survey of 1047 participants found that the number of days per week of all physical activity declined by 24% during the lockdown period. The number of minutes per day spent on physical activity decreased by 33.5% while sitting time increased by 5–8 hours among the respondents ⁴³ . Diminished physical activity levels were also reported in other countries, such as Australia ⁴⁴ , United Kingdom (UK) ⁴⁵ , and the United States (US) ^{46, 47} . Longitudinal tracking of steps among participants in a physical activity program in Australia saw a decrease in the number of steps during lockdown, which returned to normal with the lifting of restrictions ⁴⁸ . A similar improvement in physical activity levels was observed after the end of lockdown in Greece ⁴⁹ .

The work-from-home environment predisposed individuals to spend more time sitting, leaning, reclining, or lying down on the bed ¹⁷ . However, there was no predictable pattern as to who was less active during the lockdown period. While some studies found that previously physically active individuals became less active during the lockdown period ^{47, 50} , other studies found no change ⁴⁶ or reported a further reduction in physical activity among previously inactive individuals ⁵⁰ . A cross-sectional study in 64 cities in China, with 369 participants, concluded that previously physically active individuals were in greater distress because of the lockdown ⁵¹ . Studies among preschoolers ⁵² , children and adolescents in Spain ⁵³ and Brazil found a downward trend in physical activity levels and an increase in screen time/sedentary behavior among children during the lockdown period ⁴ . A similar reduction in physical activity levels among children and adolescents was also reported in studies from Canada, Germany, UK, Italy, and Spain ^{54– 59} . A study in India found a reduction in physical activity and increased screen time among men and those belonging to the upper socio-economic strata ⁶⁰ . Ironically, a study from Germany found that participants who regularly consumed alcohol and expressed greater satisfaction with their life were more physically active ⁶¹ . It was also observed that older people who were single/alone ⁶² , affected by frailty ⁶³ , used to exercising in groups, or who were not accustomed to online apps (which support exercise routines) experienced a reduction in physical activity and/or increased levels of sedentary behavior ^{64– 66} .

Lockdown provided an opportunity to be creative in finding ways to stay physically active. In South Korea, for example, it was observed that the public bicycle-sharing system recorded an increase in commuter and weekend users ⁶⁷ . It is, however, to be noted that such initiatives required commitment from citizens and authorities to ensure adherence to physical distancing, hand hygiene, facemask use, and cleaning of public facility/site surfaces. Staying physically active in home environments was possible, and its feasibility was shown during COVID-19 lockdown periods in countries like Japan ⁶⁸ , Scotland ⁶⁹ , and Switzerland ⁷⁰ , particularly among children with good parental support and encouragement. A study of 213 university students in Spain found an increase in the mean number of days they were engaged in moderate and vigorous physical activity ⁷¹ . The use of physical activity apps was useful in improving physical activity in the US ⁴⁷ . Another study of 1521 adults from the UK reported that, although most adults claimed to have maintained or increased their engagement in physical activity during the pandemic, the majority did not meet the recommended physical activity guidelines ⁷² . Studies performed in several countries, including a large study of 43,995 individuals from Brazil ⁷³ , reconfirmed that individuals who were physically active during the lockdown period were more resilient and had lower odds of suffering from stress, anxiety, and depression ^{74– 83} .

Stay-at-home restrictions affected the sleep of people in many parts of the world ^{84, 85} . A global study involving 6882 participants from 59 countries found a large proportion (66.2%) reported changes in their sleep patterns during the pandemic ⁸⁶ . In a large cross-sectional study across France, two weeks after the lockdown, 74% of the 1005 nationally representative participants reported problems trying to sleep as compared to 49% in a previous survey pre-lockdown ⁸⁷ . An Italian study including 400 university students and administrative staff reported that 40% of the respondents suffered from insomnia, while 15% specifically had issues in sleep initiation ⁸⁸ . A similar proportion (40.7%) among a sample of 1491 adults in Australia reported a negative change in sleep levels ⁴⁴ . Factors found to be associated with disturbed sleep were increased blue light exposure from extended screen time, browsing the internet to keep busy, and working remotely from home ^{88, 89} . Older age, living with a partner, and living in a higher income country were associated with better sleep health, while loss of job, challenges experienced in transitioning to working from home, being unable to pay important bills, and an increase in arguments and conflicts at home were associated with poorer sleep health ⁹⁰ . Poor sleep and anxiety/depression were found to be closely associated in a few studies ^{91– 93} .

Respondents in some studies reported sleeping more during the lockdown period. This was particularly true for preschoolers, children, and adolescents, as observed in studies from Brazil, Spain, Canada, and China ^{4, 17, 54, 55, 71} . Among adults who slept more, the reported sleep quality was poor ^{86, 94} . Those who slept more also experienced sleepiness during the day and increased daytime sleep duration, as reported in a study of 203 corporate professionals and 325 university students in India ⁹⁵ . In the same study, it was also observed that females, younger people, and those experiencing loneliness and COVID-19-related worries had greater difficulty with sleep ⁹⁵ .

Frequent awakening and increased sleeping difficulty were noted in 69.6% of 365 patients in Portugal who had pre-existing sleep-disordered breathing ⁹⁶ . One study reported an increased frequency in the uptake of sleeping pills among study participants ⁸⁷ . Increased stress due to COVID-19, information overload, inconsistent bedtime, and low mood contribute to insomnia and this has subsequent harmful effects on overall health ⁹⁶ .

A few studies reported that individuals with previously erratic sleep patterns and social jetlag, were provided with an opportunity to normalize their sleep patterns and improve sleep hygiene for optimum functioning ^{94, 97– 100} . One study from the US found that reduced rigid workload and school schedules led to an improvement in the overall sleep quality for some individuals ¹⁰¹ , and a study in Canada found students were better able to sleep and reported reduced daytime sleepiness during the lockdown ¹⁰² . A beneficial impact of quarantine on sleep was documented by a large global study of 14,000 individuals from 11 countries. A very small proportion of people were found to suffer from anxiety-induced insomnia in this study ¹⁰³ . At least one study showed that sleep problems encountered post-lockdown declined over time ⁹⁰ .

Tobacco. Few studies were available on smoking behavior during COVID-19 lockdowns. Among those available, we found variations (increases, decreases, and remaining at pre-lockdown levels) in the smoking patterns among the respondents ¹⁰⁴ . A cross-sectional study involving 345 participants in the US found that half of respondents retained their pre-lockdown level of smoking, one quarter of them reduced smoking, and the remainder increased smoking ¹⁰⁵ . The same study also found that while 20% of respondents showed an increased motivation to quit, 15% showed a reduction in motivation ¹⁰⁵ . In a study of 957 participants from the Netherlands, 14.1% reported smoking less during the pandemic, while 18.9% reported smoking more ¹⁰⁶ . In Australia, 6.9% of 1491 adults reported a negative change in their smoking habits after the introduction of lockdown measures ⁴⁴ . In a multi-country study involving 6800 combustible and e-cigarette users from Italy, India, South Africa, UK, and the US, indoor smoking had increased in India and Italy, thus increasing the risk of secondhand smoke exposure among family members ¹⁰⁷ . Anxiety, boredom, and stress experienced by many people during COVID-19 contributed to increased smoking in some individuals ^{27, 104, 108, 109} . Stress and inactivity were cited as the main reasons for increased smoking during lockdown by a cohort of patients with cardiovascular disease in France ¹¹⁰ .

Despite many deterrents, motivated individuals saw the lockdown period as an opportunity to become healthy and quit smoking ¹⁰⁵ . The motivation to quit was more discernible among those who smoked tobacco cigarettes than electronic cigarettes ¹⁰⁵ . Smokers who had a family member or someone close to them suffer from COVID-19 displayed a greater motivation to quit ¹⁰⁵ . One study reported that many parents wanted to appear on their best behavior in front of their children during lockdown and postulated that this was one of the reasons for them cutting down on their cigarette intake when spending more time at home ¹¹¹ . In a qualitative study in the US, several participants mentioned that their cessation efforts improved due to a decrease in opportunities for social smoking and because they were spending more time at home. However, other individuals in the same study claimed an increase in smoking due to lack of the same restrictions at home compared to those imposed at their workplaces ¹⁰⁴ .

Other harmful substances. Among other substances that cause dependence, alcohol stands out as one of the most used psychoactive substances during the lockdown period ^{108, 112– 114} , despite alcohol supply not being assured in many countries. A study from India documented that alcohol shop closures led to alcohol-dependent individuals experiencing withdrawal symptoms and suicides ¹¹⁵ . Where alcohol was available, some people resorted to increased alcohol intake to overcome adverse psychological outcomes of the lockdown, including stress and insomnia ^{116, 117} . Data from the Office for National Statistics in the UK demonstrates that alcohol sales rose by over 30% in month-on-month volume when compared to the previous year. In a survey of 6416 people from China, 32% of regular alcohol drinkers reported increased consumption during the lockdown period ¹¹⁸ . In Australia, 26.6% of 1491 participants reported an increase in alcohol consumption during the lockdown ⁴⁴ . A higher frequency of drinking was selectively observed in men, young adults aged 18–24 years, and those living in big cities ¹¹⁹ . A study in Italy observed that emergency admission of adolescents and young people in one hospital due to alcohol-related emergencies increased manifold during the lockdown ⁵⁶ . In a survey of 1555 people in the UK, one third reported that they had stopped or reduced drinking during the lockdown, while one fifth drank more frequently during the same period ¹²⁰ . A survey of 4072 participants in Poland found a reduced frequency of drinking in most participants ¹¹⁹ .

It was identified that those who consume alcohol found it more difficult to cope with the mental health impact of the pandemic and associated lockdowns ¹¹³ . A large study from Australia found that people who were heavy drinkers, middle-aged, and had higher incomes before the pandemic, increased drinking during the pandemic ¹²¹ . This study also found that individuals who had experienced recent job loss, were stressed/depressed, or had altered eating and sleep habits consumed larger amounts of alcohol than those who weren’t ¹²² . A study from the US found an increase in harmful alcohol use and related behaviors over the six months of lockdown-related measures ¹²³ .

A survey of 1555 patients with pre-existing alcoholic disorders in the UK concluded that ‘lockdown represents a risk factor for increased alcohol consumption in people with alcohol use disorders and relapse for those who were previously abstinent’ ¹²⁴ . Individuals who relapsed were at a high risk of harmful drinking and required a custom-tailored approach for follow-up and intervention.

A study of university students before and after university closures in the US revealed that those students who moved from on campus accommodation with peers to their homes with parents demonstrated a significant reduction in their drinking than those who remained in their pre-pandemic locations ¹²⁵ . A study of 1951 students from Belgium found that pre-lockdown drinking motives reliably predicted alcohol consumption during the lockdown ¹²⁶ .

With regard to addictive drugs, the European Monitoring Centre for Drugs and Drug Addiction determined that people using addictive drugs may be at higher risk during the crisis, particularly because of the aging cohort of opioid users and associated comorbidities. Experts also agreed that movement restrictions reduced the availability of illicit drugs ¹²⁷ , thereby increasing the demand for addiction treatment. The limited availability of these services added to the suffering of this population. There was one study from France, however, which found an increase in cannabis use among 31.2% (195 of 620) of regular cannabis users making up 5.44% (620 of 11,391) of total participants ¹²⁸ . Another study from the Netherlands found increased use of cannabis among daily cannabis users ¹²⁹ . In addition, studies have demonstrated high anxiety levels among pre-COVID-19 substance users and COVID-19 substance initiators ¹³⁰ .

Watching, reading, or listening to the constant stream of COVID-19-related news, perceived health risks ¹³¹ , and a perceived lack of autonomy ¹³² led to increased anxiety among individuals and families in many countries ^{133– 138} . The 2020 National Health Interview survey found that US adults were eight times more likely to fit the criteria for serious mental distress during the lockdown as compared to before ¹³⁹ . A study from China reported the psychological impacts of COVID-19, expressed as mild-to-severe anxiety, among 25% of 7143 college students ¹⁴⁰ . In total, 65% of 432 respondents in another study from Hong Kong reported clinical levels of depression, anxiety, and/or stress. Older adults, especially those in isolation and with cognitive decline ^{141, 142} , and their caregivers ¹⁴³ were identified to be more prone to anxiety, stress, and depression ¹³³ . A high prevalence of stress and post-traumatic stress disorders was documented among Nepalese ¹⁴⁴ , Lebanese ¹⁴⁵ , Saudi Arabian ^{146, 147} , Vietnamese ¹⁴⁸ , and Philippine nationals ¹⁴⁷ at the height of lockdown. High levels of anxiety and depression were also documented in studies from India ^{149– 151} , Ecuador ¹⁵² , Albania ¹⁵³ , Ireland ¹⁵⁴ , Hungary ⁸³ , Spain ¹⁵⁵ , Palestine ¹⁵⁶ , the UK ¹⁵⁷ , Kuwait ¹⁵⁸ , Brazil, and Portugal ¹⁵⁹ . The prevalence of people reporting clinical depression and anxiety in a sample of 1215 respondents in Italy was recorded to be 32.3% and 35.7%, respectively (compared to 15.39% and 21.40%, respectively, during pre-COVID-19 times) ¹³⁶ . A similar finding was made by another study from the country ¹⁶⁰ . One study from Jordan of 5274 participants found that four out of every ten participants in home quarantine suffered from some degree of anxiety ¹⁶¹ .

Articles also suggest that quarantined children ¹⁶² , adolescents ¹⁶³ , university students ^{164– 166} and adults ¹⁶⁷ , mothers of young children ¹⁶⁸ , and other healthy adults suffered from symptoms of poor mental health, such as post-traumatic stress, anger, and confusion ^{169, 170} . One study in Turkey found a difference in the self-reported quality of life (better) of children as opposed to the perception of their parents ¹⁷¹ . Only a few studies made a clear distinction between the stress levels experienced by the general population as part of the community quarantine versus those who were quarantined as part of contact tracing or after testing COVID-19 positive. A few studies seem to suggest greater stress experienced by both those under isolation ^{172, 173} and others under home quarantine as part of contact tracing ¹⁷⁴ . One study from China, however, found that home self-quarantine was associated with increased happiness as compared to those who were in community quarantine ¹⁷⁵ . A study from the UK found that a majority of the older people interviewed identified positive aspects of lockdown and felt better prepared to deal with the lockdown ¹⁷⁶ .

Higher stress levels associated with lockdown measures were observed in some groups, such as women ^{177– 180} (particularly pregnant women ¹⁸¹ , single/divorced adults ⁷⁶ , older people (particularly with pre-existing mental health conditions ^{154, 167} ), parents with young children ¹⁸² , university students and young adults ^{183– 185} , workers ¹⁸⁶ , those self-medicating ¹⁸⁷ , the economically deprived ¹³⁷ , those with pre-existing depression ¹⁸⁸ , bipolar disorders ¹⁸⁹ , and other chronic medical conditions ^{133, 180, 190– 192} . A large study of 56,679 participants in China found that quarantine had a profound effect on the mental health of specific vulnerable groups, including those with pre-existing mental disorders, chronic physical diseases, frontline workers, and those living in the most affected areas ¹⁹³ . A similar large study of 53,524 participants from 26 countries during the pandemic found higher levels of stress associated with being young, female gender, lower level of education, being single, number of children in the family, and living in a country experiencing severe community spread ¹⁹⁴ .

Extreme stress driven by fear of COVID-19 infection, financial crisis, loneliness, the pressure to quarantine and isolate when tested positive, stigma, and the unavailability of alcohol were identified as drivers of suicidal ideation and suicide during the pandemic and the associated lockdowns ^{173, 195– 197} . A healthy diet and refraining from reading updates about COVID-19 were very often shown to be the best predictors of lower levels of anxiety and depressive symptoms ¹⁹⁸ . A longitudinal study reported that fear of COVID-19 decreased over time since the introduction of lockdown, but depression levels increased in a cohort of Chinese individuals ¹⁸⁹ . There were mixed results from New Zealand, one of the countries known to have best managed the pandemic, where 62% of those surveyed in a study reported ‘silver linings’ during the lockdown, such as enjoying working from home and a less polluted environment, while the same study found 16% of participants suffered from anxiety and 39% reported low well-being ¹⁹⁹ . A qualitative study from Italy found that, beyond the difficulties associated with lockdown, parents of children with neurodevelopmental disorders appreciated spending more quality time with their children, thus contributing to enhanced parent-child relationships ²⁰⁰ . Some longitudinal studies found the mental health of individuals improved over time as extreme fear and the sense of emergency subsided ²⁰¹ .

The restriction of movement during the pandemic led to a significant reduction in social activity among family, friends/neighbors, and for entertainment ^{202, 203} . This contributed to diminished life satisfaction in >30% of participants in a large, multi-continent study involving 1047 participants ²⁰³ . A study of 571 healthy adults in Israel found greater psychological distress, poor connectedness, and lowered resilience among women, young adults, and the unemployed ²⁰⁴ . An online survey of 309 residents in Europe and the US revealed that 100% of participants faced some degree of social isolation during the lockdown period. This study found that younger adults (aged 18–29) reported higher self-isolation than older groups. Those feeling socially isolated were also less satisfied with their food habits, work, and housing ²⁰⁵ . Prolonged social media use had a deleterious effect on the overall social well being of individuals as reported by studies in Saudi Arabia ²⁰² and Italy ²⁰⁶ .

A study in Finland ²⁰⁷ found that families used two types of coping during the lockdown – family conversations and family time. Family time, defined as “doing things together,” was more prevalent on weekends, when families preferred to do outdoor activities, such as playing together A study in Canada ²⁰⁸ found that time spent on the internet and video games by children increased during lockdown periods. No studies during the review period explicitly documented changes in other positive indoor behaviors, such as yoga and meditation.

Studies found that a lack of social interaction had a more profound effect on people with higher income and education ²⁰⁴ . Lack of social interaction also had a negative impact as more time passes for older people, as evidenced by large cross-sectional studies in the UK ^{209, 210} and Switzerland ²¹¹ . Children and adolescents reported being more restless, irritable, and inattentive during the lockdown ²¹² with increased screen time being the likely contributor ^{213, 214} along with worsening of relationships ²¹⁵ and dysfunctional parenting ²¹⁶ . Girls and women confined to homes and quarantine facilities faced increased family tensions, an overload of domestic work, and were vulnerable to physical and emotional abuse ²¹⁷ . Intimate partner violence—characterized by physical, sexual, or emotional violence between partners—was also of concern during challenging times of staying home and with physical distancing ²¹⁸ . A study in Switzerland found that older adults who managed to maintain social communication at a satisfactory level were able to manage their stress level, thus underscoring the importance of social connectedness ²¹¹ .

Studies show that patients with pre-existing NCDs found it difficult to maintain a healthy lifestyle during the COVID-19 pandemic and associated lockdown measures introduced by countries ²¹⁹ . Patients with coronary heart disease ^{220– 222} , neurological disorders ^{223, 224} , diabetes ^{225, 226} and cancer ^{227, 228} had to compromise on their physical activity routine, dietary patterns, and social connectedness in particular ^{219, 226, 229, 230} , as did families with children who had chronic respiratory diseases ^{184, 231} . Poor glycemic control in diabetics due to altered lifestyle was reported in many studies ^{232– 238} , while one study in India reported an improvement in the glycemic status of patients with type II diabetes mellitus ²³⁹ . In a study from France, 45% of 195 patients with chronic heart disease had a >25% reduction in physical activity and 24% of patients had gained >2kg weight ²⁴⁰ . A study of parents of 125 children with disabilities in the UK found that 61% of them reporting a reduction in physical activity levels and over 90% reported a negative impact on their children’s mental health ²⁴¹ . A qualitative study in Ireland came to a similar conclusion regarding increased mental health difficulties among children with Autistic Spectrum Disorder ^{242, 243} . Patients fearful of acquiring COVID-19 infection were also found to postpone medical care for their chronic problems ²⁴⁴ , leading to greater physical and psychological distress, while adding to the suffering of chronically ill patients ^{219, 245, 246} . Some studies found an improvement in patients with conditions such as migraine ^{247, 248} , whereas other studies found limited or no change in the lifestyle of those with other chronic diseases ²⁴⁹ .

This narrative review is a comprehensive analysis of the existing literature on the impact of COVID-19-related lockdown on the lifestyles of people globally. As the review is narrative, we included all the relevant and available published literature on the subject to ensure comprehensiveness. We did not undertake quality assessment of each of the publications; instead, we used data as reported in the articles. Most of the studies included in our review are observational, which is an inherent limitation of the review study design. Despite this general limitation—as is the case with all narrative reviews—we do not consider this a major impediment to our research pursuit, as our analysis relies largely on trends and qualitative aspects of data. Given the global nature of the review, we also acknowledge that the studies included are from various countries and cultures and, hence, cannot be generalized. We have identified patterns, where possible, and we hope, will have broad global implications and specific local implications. We only searched two databases for the study and with the huge volume of studies in this broad subject, it is possible we might have inadvertently missed some studies in our synthesis. The point of concept saturation was based on judgement of the authors though acceptable in an interpretivist paradigm, this can be seen as a limitation in a positivist paradigm. We also acknowledge that home quarantine, institutional quarantine, community quarantine, and isolation can each have different levels of impact on lifestyles, but did not find an adequate number of studies in each category to analyze them separately.