Working Against the Clock

We live at a paradoxical moment. We have never known more about sleep, and we have rarely slept as badly.

Alfredo Rodríguez-Muñoz is Professor of Psychology at the Universidad Complutense de Madrid and author of Dormir para vivir. La ciencia del sueño. In his conversation with SALUZ, he described sleep problems as a public health issue in Spain. He cited estimates that around half of the population experiences sleep problems and that between 15% and 20% suffer from chronic insomnia.

Much of the conversation about sleep focuses on the individual: better habits, a cooler bedroom, less caffeine. Alfredo's argument starts somewhere else. Sleep does not happen in a vacuum. It depends on the context in which we live, and for most professionals, that context is shaped by work.

Sleep is decided during the day

A central idea in Alfredo's episode is that sleep depends on what happens during the day: what and when we eat, how much we move, and how much natural light we are exposed to.

Light is a clear example. As Alfredo explained, blue light inhibits the production of melatonin, the hormone that helps signal to the body that it is time to sleep. According to him, using a phone before bed can delay its release by up to an hour and a half. The evening screen is only half of the problem. The other half is the day spent indoors under artificial light, far from the natural daylight that helps set the body's internal clock.

He also described a broader tension: our circadian rhythms — the roughly 24-hour cycles that regulate sleep, alertness, hormones and metabolism — increasingly conflict with the way modern society is organised. Work plays a central role in that conflict.

What the data says about working people

The picture Alfredo describes shows up in workplace data. In Deloitte's 2023 Well-being at Work survey of 3,150 workers, managers and executives across four countries, only 45% of respondents said they always or often get at least seven hours of sleep. Nearly three-quarters (74%) said they struggle to take time off or disconnect from work.

These findings are connected. When work follows people home through screens and notifications, evening light exposure increases, the mind stays switched on, and the time available for sleep shrinks.

Employers are in a position to act on this. The McKinsey Health Institute lists sleep among six modifiable drivers of health through which employers can have a considerable impact, alongside social interaction, mindsets and beliefs, productive activity, stress and economic security.

Why a tired brain is a business issue

The cost of lost sleep does not stay in the bedroom. A classic study by Williamson and Feyer compared the effects of sleep deprivation and alcohol in the same participants. After 17 to 19 hours awake, performance on some tests was equal to or worse than performance at a blood alcohol concentration of 0.05%.

Seventeen to nineteen hours is not an extreme scenario. For someone who wakes at 6am, it corresponds to answering emails between 11pm and 1am — something many professionals would recognise.

The effect is not uniform. Simpler tasks such as reaction time were much more affected by sleep deprivation than higher cognitive skills such as logical reasoning and memory. This nuance matters: the first signs of fatigue may not appear in a strategy discussion, but they will appear in attention, speed and accuracy — the building blocks of daily work.

The organisation has a clock too

If sleep is shaped by context, every organisation is making decisions about its people's sleep, whether it intends to or not. These decisions include:

• Early meetings, which cut into the sleep of people whose internal clocks run later.
• Late emails and messages, which keep screens lit and minds active in the evening.
• Travel across time zones and irregular schedules, which repeatedly disrupt circadian rhythms.
• A culture where being available at all hours is seen as commitment.

These are features of how work is designed. Changing them does not require a separate programme. It requires leaders to recognise that the schedule itself is a biological intervention.

What this means for organisations

Alfredo's work points to a simple reframe: sleep is not what happens after work. It is the foundation that determines what people can bring to work the next day. Organisations that want sustained attention, sound judgement and stable performance have a direct interest in the conditions that make good sleep possible.

At SALUZ, we believe understanding this should be part of how leaders are educated, because they shape the working day, and the working day shapes the night.

A note on the evidence

The figures on sleep problems in Spain are cited from Alfredo Rodríguez-Muñoz's conversation with SALUZ. The Deloitte data is self-reported and comes from four English-speaking countries, so it should not be extrapolated directly to Spain. The Williamson and Feyer study was conducted in 2000 with 39 participants, mostly from the transport industry and the army, and measured continuous wakefulness rather than chronic short sleep.

Sources

• Williamson, A. M. & Feyer, A.-M. (2000). ‘Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication.’ Occupational and Environmental Medicine, 57(10).
• Deloitte Insights, Well-being at Work survey (2023).
• McKinsey Health Institute, ‘Working nine to thrive.’