Sleep, recovery and absence risk

Sleep is where recovery happens. It's also one of the first things to slip when people are under sustained pressure, and one of the clearest early signals we have.

Why sleep matters at work

Sleep affects concentration, mood, decision-making, reaction time and how people cope with stress. When it's consistently short or broken, performance suffers long before anyone takes a sick day.

In shift-based sectors such as healthcare and logistics, fatigue is also a safety issue. In knowledge work, it shows up as slower thinking, more mistakes and shorter tempers.

The link to absence

Research has examined the link between sleep problems and later sickness absence, including work by Madsen and colleagues (2016), listed on our Science page. The general picture from this kind of research is that sleep problems are associated with a greater likelihood of future absence. That makes sleep a useful early indicator, not just a wellbeing nice-to-have.

Noise versus signal

Everyone has bad nights. A late flight, a sick child or a deadline. Reacting to single nights would create noise and anxiety.

What matters is a sustained change against a person's own baseline. For example:

• sleep that is consistently shorter than usual for several weeks,
• sleep efficiency that keeps falling,
• overnight heart rate that sits higher than normal,
• HRV that drifts below baseline at the same time.

When several of these move together, recovery probably isn't keeping up with load.

What wearables can and can't tell us

Consumer wearables are reasonably good at estimating total sleep time and sleep timing. They are less accurate at classifying sleep stages. Schyvens and colleagues (2024) compared consumer sleep trackers with polysomnography, the clinical gold standard, and found the same broad pattern. So we focus on the measures wearables do well, and we read trends over time rather than nightly stage breakdowns.

We pair wearable data with the Pittsburgh Sleep Quality Index style of validated self-report, so what the device shows is checked against what the person experiences.

What happens when sleep drifts

The person sees it first, privately, with practical guidance on sleep and recovery that fits their situation. If the pattern holds, an Everis physiologist can check in. If something needs medical attention, they refer to a clinician.

Employers never see an individual's sleep data.

What this means for your organisation

At team level, the Sleep Quality Index shows whether sleep is improving or slipping across departments. Combined with workload and stress indices, it helps leaders see where scheduling, shift patterns or workload might need a closer look, and gives the Everis Engine one of its most useful inputs for projecting absence risk.

Sources: Madsen IEH et al. (2016); Schyvens AM et al. (2024). Full references on our Science page.