Winter blues at work: what to do before January

Absence in winter is flu, and there is little an organisation can do about it. That is the common assumption, and in part it holds. Flu fills the sick reports. But the damage sits in long-term absence, and that more often has to do with the work. Winter blues in your team are then a first signal. What matters is the winter load of the work: light, recovery and staffing.

Why is absence higher in winter?

Absence follows a fixed pattern. In the Netherlands in 2025, it stood at 5.8% in the first quarter and 5.1% in the third quarter. That is a difference of 0.7 percentage points (CBS, 2026a). The fourth quarter came in at 5.6%.

Statistics Netherlands (CBS) speaks of a seasonal effect: more people are off sick in winter than in summer. That is why it always compares a quarter with the same quarter of earlier years (CBS, 2026b).

A large part of the explanation is the flu season. The RIVM, the Dutch National Institute for Public Health and the Environment, runs the respiratory season from week 40 to week 20. That is roughly from early October to mid-May (RIVM, 2026). In 2025, 55% of employees on sick leave named flu, a cold or another viral infection as their main complaint (CBS, 2026b).

So the season is long. The epidemic itself is shorter. In 2026 it started at the end of January and lasted six weeks. A year earlier it lasted nine weeks (Nivel, 2026). It is hard to predict when the peak will fall. You can prepare, though, because a team often runs with little reserve in the dark months.

Is sickness absence in winter just flu?

In terms of the number of sick reports, largely yes. Flu and colds account for 55.2% of absence. They last 3 working days on average. Only 11% is attributed to the work (Van den Heuvel et al., 2025, figures for 2023).

Absence due to mental health complaints, overstrain and burnout is 7.9% of the total. It lasts 63 working days on average. In 75% of cases it is partly or mainly attributed to the work (Van den Heuvel et al., 2025). So the short reports fill the statistics. The long-term absence determines the damage. Also read what causes burnout and what an employer can do about it.

Note what this does not say. There is no evidence that absence due to mental health complaints is higher in winter than in summer. The reasoning is simple, though. When short reports thin out a team, colleagues share out the work. The pressure lands on whoever stays. A team with little reserve notices that first.

The figures on workload point the same way. High workload and infection at work are among the most frequently cited causes of work-related absence (Arboportaal, 2026). Both can partly be influenced. The share of employees with burnout complaints rose to 21% in 2025, against 19% in 2023 (Arboportaal, 2026).

For the board, the cost counts too. In 2023, employers paid € 8.3 billion in wages during work-related absence. Of that, € 4.9 billion came from psychosocial workload (Van den Heuvel et al., 2025).

What are winter blues, and how do they differ from seasonal depression?

Winter blues is the everyday name for low energy in winter. You get tired more quickly and feel less motivated. You also hear the terms winter dip and autumn dip. Winter blues is not a diagnosis and not an illness.

Seasonal depression, also known as seasonal affective disorder (SAD), is. According to Thuisarts, the Dutch GP information site, you then have a depression in autumn or winter two years in a row. It goes away again in spring. The cause is probably less daylight. People then have no energy, feel very tired and want to sleep a lot (Thuisarts, n.d.). The NHS describes it in the same way. Light therapy is not routinely available there, because the evidence is too limited (NHS, n.d.).

For HR, that means: do not diagnose, and do not ask about it. A team leader sees behaviour, not the cause. Anyone who has felt low for more than a few weeks belongs with their GP or occupational physician. The conversation with the employee is about the work and what they need. A dip in energy can be discussed; a depression belongs with a professional. As HR, you make sure the route to the GP or occupational physician is short.

Why is light also a working condition?

According to the KNMI table, around 21 December the sun rises at about 8:45 am and sets at 4:30 pm in the Netherlands (KNMI, n.d.). That is less than eight hours of daylight. Anyone working nine to five travels there and back in the dark.

The Arboportaal, the Dutch occupational health portal, writes that the positive effects of light apply mainly to daylight. It advises exposing employees to daylight as much as possible (Arboportaal, n.d.). Artificial light has a lower intensity.

How much absence this saves is not known. The measures are small and cheap, though:

• Break outside. A quarter of an hour in the light, even when it is grey.
• Walking meetings. A meeting that does not need a table can take place outside and in daytime.
• Workstations by the window. Rotate them, so that it does not become a fixed favourite spot.
• Early shifts and night shifts. In healthcare and shift work, people see little daylight in December. Look at this separately, because a rota with changing shifts leaves little room for a break in the light.

The team leader who makes the rota does their best with the staff they have. Light is rarely in that rota. It can be, if someone raises it.

That applies to healthcare, where shifts change, and to production, where teams work fixed hours. A team that starts at 6:00 am and finishes at 2:30 pm sees little daylight in December. The question is not who is to blame, but where a quarter of an hour outside fits.

What can you do as HR before January?

You do not need to wait until spring. You arrange this in November:

• Staffing. Agree in advance who covers and who takes over what in the flu weeks. Then the team leader does not have to arrange it in the middle of the peak.
• Recovery. Schedule rest around the turn of the year, and do not count on it happening by itself.
• Signals. Ask team leaders to watch for tiredness, withdrawal and a short temper. Also read how to spot work stress earlier.
• Energy. Ask how things are going. One question is enough.

Winter blues are no reason to panic, but they are a reason to pay attention. It is about what you can plan into the work, not about what happens to your employees in private. Whoever builds winter into the planning as a season has more room in January. Whoever waits for the first absence does not.

If you ask employees, keep it short and anonymous. Do not split out the results for small groups. Say beforehand what will happen with the answers. Discuss the absence policy and what is recorded with the works council.

Think of the employee who fills it in, too. Why would they answer honestly? Only if they know the answer cannot be traced back to them. And that something happens with it afterwards. An example question: how was your energy over the past weeks, on a scale of 1 to 5?

What can you do tomorrow? In the next team leaders’ meeting, go through the winter weeks with the checklist above. That is all the first time needs to be.

Getting started

With the Reduce absenteeism module in Deepler Research, you ask employees anonymously which work factors influence absenteeism in their team. Want to read more about recovery first? Then read How to switch off from work when always reachable.

Sources

• Arboportaal. (n.d.). Daglicht of kunstlicht? https://www.arboportaal.nl/documenten/vraag-en-antwoord/alle-vragen-en-antwoorden/daglicht-of-kunstlicht
• Arboportaal. (2026, 20 April). Burn-outklachten onder werknemers blijven toenemen. https://www.arboportaal.nl/actueel/nieuws/2026/04/20/burn-outklachten-onder-werknemers-blijven-toenemen
• Centraal Bureau voor de Statistiek. (2026a). Ziekteverzuimpercentage; economische activiteit (SBI 2008) [Table 80072NED]. https://www.cbs.nl/nl-nl/cijfers/detail/80072ned
• Centraal Bureau voor de Statistiek. (2026b). Ziekteverzuim in eerste kwartaal hoger dan gemiddeld in afgelopen 30 jaar. https://www.cbs.nl/nl-nl/nieuws/2026/23/ziekteverzuim-in-eerste-kwartaal-hoger-dan-gemiddeld-in-afgelopen-30-jaar
• Koninklijk Nederlands Meteorologisch Instituut. (n.d.). Tijden van zonopkomst en ondergang 2027 [Table]. https://cdn.knmi.nl/system/downloads/files/000/000/081/original/tijden_van_zonopkomst_en_-ondergang_2027.pdf
• National Health Service. (n.d.). Seasonal affective disorder (SAD). https://www.nhs.uk/mental-health/conditions/seasonal-affective-disorder-sad/overview/
• Nivel. (2026, 18 March). Duidelijk minder mensen met acute luchtweginfecties, jaarlijkse griepepidemie voorbij. https://www.nivel.nl/nl/nieuws/duidelijk-minder-mensen-met-acute-luchtweginfecties-jaarlijkse-griepepidemie-voorbij
• Rijksinstituut voor Volksgezondheid en Milieu. (2026). Terugblik surveillance van luchtweginfecties 2025/2026 – Influenzavirus. https://www.rivm.nl/griep-griepprik/griepsurveillance/terugblik-2025-2026
• Thuisarts.nl. (n.d.). Ik heb een winterdepressie, wat helpt ertegen? https://www.thuisarts.nl/winterdepressie/ik-heb-winterdepressie
• Van den Heuvel, S. G., Bouwens, L., & De Vroome, E. M. M. (2025). Arbobalans 2024 (TNO 2025 R11108). TNO. https://monitorarbeid.tno.nl/wp-content/uploads/sites/16/2025/05/TNO-Arbobalans-2024.pdf