A century ago, the five-day working week helped reshape society. It was introduced at scale by industrial pioneers to address not only worker wellbeing but also economic pressures.

US industrialist Henry Ford was among the first to give workers two full days off per week, 100 years ago this month. Ford suspected that giving workers a “weekend” would increase overall productivity – and he was correct.

Today, as advances in artificial intelligence accelerate and concerns about job security grow, a similar question is emerging. Could reducing working time again help societies adapt to these seismic changes?

The evidence increasingly suggests it can, but not in the simplistic way that is often portrayed. The four-day week is not just a workplace benefit. It is a potential tool to improve wellbeing, support families and rethink how work is distributed in society.

Research across multiple countries, including large-scale pilots in the UK and Portugal, shows that reducing working time can deliver meaningful benefits for both employees and organisations.

In a 2025 study of four-day week adoption, my colleagues and I found improvements in sleep, exercise and quality of working life. There were positive implications for both the mental and physical health of employees.

Our research showed productivity at work can also increase, alongside reductions in absenteeism and staff turnover. And it can be beneficial for an employer’s social image.

However, the most important insight is not about productivity but what happens outside work. After all, time is a social resource, not just an economic one.

When people move to a four-day week, they do not simply rest more. They reallocate time in ways that have broader implications for society.

Across our research, participants said they spend more time with family and friends, engaging in community activities and investing in their physical and mental health by exercising and practising hobbies and self-care activities.

These are not trivial changes. Over time, they contribute to stronger social ties, better mental health and more resilient communities.

There are also important gender implications. Early findings suggest that reduced working time can lead to fathers being more involved in caring for their children and other domestic responsibilities. While this does not automatically solve gender inequality, it creates conditions that make more equal divisions of labour possible.

In this sense, the four-day week is not just about work. It is about how societies organise care, relationships and everyday life.

The challenge in service sectors

Critics of a four-day week often point out that it is harder to implement in service sectors such as healthcare, childcare, manufacturing, hospitality or retail. This is true, but it is not a reason to dismiss the idea.

In these sectors, work is tied to time, presence and staffing levels. Reducing working hours often requires more complex redesign, including changes to rotas, additional hiring or upfront investment. Colleagues and I have highlighted this when addressing the UK case of the NHS.

But these challenges should be seen as design problems, not impossibilities. In fact, the potential benefits to society may be even greater in these sectors. Improved wellbeing and reduced burnout among healthcare staff and care workers can translate into better quality of service and fewer mistakes.

A more important concern is inequality. If working time reductions are adopted unevenly, there is a risk that some workers will be excluded – often those in lower-paid or frontline roles. This is a valid concern, but not an argument against the four-day week. Rather, it is an argument for implementing it more thoughtfully.

Instead of asking whether all jobs can adopt the same model, the focus should be on how different forms of reduced work time can be adapted across sectors. This could include shorter daily hours, staggered schedules or phased time reductions.

The future of work

The renewed interest in reducing the amount of time we spend working is not happening in isolation. It is closely linked to broader debates about automation, productivity and the future of work.

If technological advances continue to increase productivity, a fundamental question arises: who benefits from these gains?

Historically – during the Great Depression, for example – working time reductions have been one way of redistributing those benefits. Compared with more radical proposals such as universal basic income, the four-day week offers a more direct and socially embedded way of sharing gains in productivity.

The four-day week is not a universal solution, and it will not look the same everywhere. But the evidence shows working less can go hand-in-hand with maintaining productivity.

It can also support a shift towards a society where time is valued not only as an economic input, but as a foundation for wellbeing, relationships and participation in community life.

A century after the five-day week helped define modern work, there may be another turning point on the horizon. This time, the real question is not whether we can afford to reduce working time, but whether we can afford not to.

Rita Fontinha’s employer, the University of Reading, has received funding from the Portuguese Government and the Azores Regional Government to conduct academic research on four-day working week pilots.

At the time of the dinosaurs, the oceans were teeming with life. Below the waves, giant marine reptiles, such as the fearsome 4m (13ft) long mosasaurs, were the undisputed apex predators.

In artistic reconstructions of these ancient oceans, cephalopods – the animal group that includes squid, cuttlefish, octopuses, and their ancestors – are almost always portrayed as prey, often seen desperately swimming away from the jaws of a marine reptile to avoid becoming lunch.

However, a remarkable new fossil suggests our view of the ancient oceans is incomplete, and that giant octopuses, perhaps reaching as long as 19m (62ft), may have been the ones doing the hunting.

The fossil in question is a giant octopus jaw, belonging to a new species called Nanaimoteuthis haggarti. It is found in Late Cretaceous rocks of Japan, making it between 100 million and 72 million years old.

Like other cephalopods, octopuses have a hard beak that looks like a parrot’s bill, used to bite and tear prey, and this fossil example is enormous – larger than that of the famous giant squid Architeuthis.

Based on the shape and size of the beak, Shin Ikegami, from Hokkaido University, Japan, and colleagues, identify it as belonging to the Cirrata, a group of finned octopuses still found today in the deepest oceans. They estimate that the animal may have reached between seven and 19 metres in length. Details have been published in the journal Science.

If that upper estimate is even close to correct, Nanaimoteuthis, would represent the largest invertebrate yet described from the fossil record — an animal rivalling the largest marine reptiles in scale.

The authors also use the wear and damage on the octopus beak as indicators of ancient behaviour. Scratches and pits on the surface point to an animal hunting and crushing prey with bones or shells, not scavenging or feeding on soft-bodied organisms.

Additionally, the wear pattern is asymmetric, interpreted by the authors as evidence of a preference for chewing on one side over the other, a trait associated with higher cognitive function.

Far from being food, Nanaimoteuthis may have been one of the most formidable predators in its ecosystem, in an era we have long assumed was defined by vertebrate dominance.

That such a claim can be made at all is remarkable, because cephalopods almost never leave any trace in the fossil record. Unlike fish, marine reptiles, or even ammonites, most cephalopods have no hard parts like bones.

Octopuses, in particular, are almost entirely “skin bags” filled with water. When they die, they rot quickly, and even the few hard parts, such as the beak, are seldom preserved.

This creates a systematic bias that skews our understanding of ancient ecosystems: animals that preserve well dominate our reconstructions, and the animals that don’t, even if they were common among certain ancient ecosystems, are largely invisible to us.

Every fossil cephalopod, therefore, represents a vital piece of palaeontological information, giving us a fleeting glimpse into a lost world of squishy invertebrates.

But not all cephalopodologists are convinced by the size estimate, with the potential length of 19m in particular drawing scrutiny on social media.

Scaling cephalopod body sizes from beaks is not straightforward. The relationship between jaw dimensions and total body size varies considerably across cephalopod species, a problem compounded by the patchy data available for rarely caught deep-water cirrate octopuses.

Other researchers have also questioned the behavioural inferences drawn from the wear patterns, arguing that bite asymmetry can be caused by many factors, and that drawing conclusions about animal intelligence from a single specimen is premature.

It is also important to put this finding into context of the living relatives of Nanaimoteuthis. Modern cirrate octopuses are not known to swim after prey, typically hunting small invertebrates on the seafloor, raising questions about whether their giant ancient cousins would ever have encountered, let alone challenged, the formidable marine reptiles.

But step back from the debate over metres and scaling equations, and something fundamental comes into view. Our reconstructions of ancient ecosystems are shaped by what preserves (bones, shells, teeth) and often systematically blind to what doesn’t.

While future investigations may test the size estimate or refine behavioural interpretations, this remarkable fossil shows that there may have been giants lurking in the vast, deep, and dark waters of the ancient oceans. We just couldn’t see them until now.

Thomas Clements does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.