In this episode closing Season Ten of the Data Malarkey podcast, Master Data Storyteller, Sam Knowles, spoke to Charlotte Rae, Associate Professor in Psychology at the University of Sussex, on the reality of what the data reveal about the four-day working week. What emerges is not a lifestyle trend, nor a simple perk, but a structured, evidence-based shift in how work is organised and experienced.
The 100:80:100 model
Rae’s work centres on the Sussex 4 Day Week research programme, which examines the impact of reducing working time while maintaining salary and performance expectations. This “100:80:100” model requires individuals – and so organisations – to achieve the same outcomes in less time. It is not about compressing hours to pro-rata salaries, nor about part-time working, but about finding efficiencies that make better use of human capacity.
The process begins before any change in working pattern. Organisations are encouraged to examine how work is currently done, identifying friction points in meetings, email and technology habits, and task prioritisation. These are rarely dramatic changes. Instead, small, cumulative adjustments (so-called marginal gains) reshape how time is used to help – in the words of the celebrated book – “make the boat go faster”. Staff are closely involved in this process, recognising that those doing the work often hold the clearest view of where inefficiencies lie.
Learning by doing
Once a trial begins, Rae and her team collect baseline data, then track changes over a 12-week period. The results are measured across wellbeing, sleep, motivation, and productivity. One consistent finding is that productivity, defined as goal achievement, tends to increase modestly, on average by around 8 per cent. Crucially, this is not universal. Some organisations maintain performance, others exceed it, and a minority see declines. The variation reflects the complexity of organisational life rather than a single universal outcome.
How we can do more in less time
Two mechanisms underpin the improvements that are observed. The first is physiological. Better sleep and longer recovery enable individuals to work with greater focus and clarity. The second is motivational. The prospect of an additional day away from work acts as a powerful incentive, encouraging more disciplined and intentional behaviour during working hours – “less faffing around”, as Sam puts it. Together, these factors support a shift towards higher-value work and away from low-impact activity.
The additional day itself is rarely used for commercial gain. Most participants report spending time on restorative activities, including family, exercise, and hobbies. These contribute to what psychologists describe as conscious recovery, complementing the benefits of sleep. Some employers’ concerns about widespread “side hustles” appear largely unfounded.
Different strokes for different folks
Adoption varies by organisational size and sector. Smaller businesses, with higher levels of trust and fewer structural complexities, tend to find the transition easier. Larger organisations can implement similar changes but often require more extensive preparation and coordination, or else a rolling programme moving from department to department rather than everyone everywhere all at once. Knowledge-based roles are more commonly represented in Charlotte’s cohort, although examples from manufacturing and care settings demonstrate that the model can be adapted more widely.
Importantly, the four-day week is not a fixed template. Organisations choose different non-working days, stagger schedules, or adapt the model to seasonal demands. Flexibility, rather than uniformity, appears to be the key to success.
Motivated behaviour change
Looking ahead, Rae sees potential for technologies such as AI to support these efficiencies, but only where they are applied thoughtfully. Tools alone do not create change. Behaviour, structure, and intention remain central.
Perhaps the most striking finding is persistence. Six months after trials conclude, around 80 per cent of organisations continue with the model, with benefits maintained or even improved. The evidence suggests that, when implemented carefully, the four-day week is not a temporary adjustment, but a sustainable rethinking of work itself.
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The first draft of this blog was written by ChatGPT, using a transcript of the episode and an ever-refined prompt. It was then edited by real humans.