When young adults start working, the amount of daily physical activity they do increases sharply, only to fall away again over the new few years, while the amount of sleep they get falls slightly, according to new research led by scientists at the University of Cambridge.
If we want to stay healthy throughout our lives, we need to remember that keeping active is an important way of helping us achieve this goal
Alena Oxenham
The increase in physical activity was mainly seen in those doing semi-routine occupations such as bus driving or hairdressing, and routine occupations such as cleaning or waiting, or technical jobs. There was little change seen among people entering managerial or professional occupations.
People who work from home saw a decrease in levels of physical activity - though their sleep levels did not change when they started work.
Young adulthood - ages 16 to 30 years - is an important time in terms of health. Although we are typically at our peak physical health, it is also a time when many risk factors for long term diseases such as heart disease, type 2 diabetes and cancer begin to develop.
Health guidelines recommend young adults get between seven and nine hours of sleep a night, engage in 150 minutes or more of moderate physical activity per week, and consume at least five portions of fruit and vegetables per day.
Young adulthood is also the time when most people start work, which changes their daily routines and activities, resources such as time and money, and social and physical environments - all of which affect health behaviours and health in later life.
To quantify the impact that starting work has on health-related behaviours, a team led by researchers at the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge examined repeated data taken over time from more than 3,000 participants in the UK Household Longitudinal Study. All the participants were aged 16-30 years and started work for the first time between 2015 and 2023.
The results are published today in the International Journal of Behavioral Nutrition and Physical Activity.
Dr Eleanor Winpenny, who was based at the University of Cambridge when she carried out the work, but is now at Imperial College London, said: "We know about physical activity and sleep patterns among young people while they're at school, but very little about what happens when they start work. Given the impact that work can have on our lives - and the lasting impacts this can have on our health - it's important to try and understand what happens at this transition."
The analysis showed that when people started work, their physical activity increased by an amount equivalent to around 28 min of moderate activity (such as cycling) per day on average - but then decreased each year after starting work by around 7 min per day.
The biggest increase was among males - up by an equivalent of around 45 min of moderate activity per day compared to an increase of around 16 min for females. People who did not have a university degree also showed a greater increase in physical activity compared to those with a university degree - equivalent to around a 42 min increase of moderate physical activity per day compared to 15 min per day.
Working from home, however, appeared to be associated with an initial decrease in physical activity, equivalent to around 32 min of moderate activity per day.
When young adults started work, the amount of time they slept per night dropped immediately by almost 10 minutes and remained stable at this level over time; however, people without a degree showed a continuing decrease of about 3 minutes of sleep per night each year after starting work, while those with a degree slowly increased back to their pre-work sleep levels.
There was little change in the amount of fruit and vegetables consumed after starting work.
Alena Oxenham, from the MRC Epidemiology Unit, said: "Beginning work can have a profound impact on our lifestyles and on behaviours that might make a difference to our health, if not immediately then later in life.
"Although we found that people tend to do more physical activity when they begin work, which is good news, these are averages, and some people - particularly those who work from home and, to a lesser degree, those with office-based jobs - may do less.
"If we want to stay healthy throughout our lives, we need to remember that keeping active is an important way of helping us achieve this goal. Those working at home might want to consider incorporating physical activity into their day, for example by going for a walk before or after work, or during a lunch break."
Dr Winpenny added: "Workplaces provide an opportunity to create environments and cultures that support healthier diets, more physical activity and better sleep for young adults. This could result in healthier employees and fewer sick days in the immediate term, but also have long term benefits, helping prevent health issues in later life."
The research was funded by the MRC and the National Institute for Health and Care Research.
Reference
Oxenham, AF, et al. New job, new habits? A multilevel interrupted time series analysis of changes in diet, physical activity and sleep among young adults starting work for the first time. International Journal of Behavioral Nutrition and Physical Activity; 28 Jan 2025; DOI: 10.1186/s12966-024-01682-8
