Every autumn, business owners notice the same thing. As the evenings grow longer and darker, the office feels flatter. People are slower to start, quicker to drift, and the 4 pm slump arrives at 3 pm. It’s tempting to put that down to mood or motivation. Most of it is biology, and it is easier to change than you might think. Dr Ramona von Leden, PhD, neuroscientist and scientific advisor to Neuronic, provides some advice.

What the dark actually does

The human brain sets its internal clock by light, specifically by bright light reaching the eye in the morning. That signal tells the body when to be alert and, roughly 14 to 16 hours later, when to release melatonin and wind down. In summer most of us get that morning signal without trying, from the early rising sun. From November to February, many people leave home while it’s still dark, sit under indoor lighting that is a fraction of the intensity of daylight, and leave work in the dark again. Our clock never gets a clear start to the day, so alertness, mood and sleep all lose their edge.

The days naturally get shorter as we move into winter, but the one-hour shift when the clocks change makes this normal seasonal transition more pronounced for a week or two. Research on daylight saving transitions shows temporary disruptions to sleep and cognitive performance in the days after a change, and a rise in errors and accidents [1, 2]. While the increased risk of workplace accidents is more consistently associated with the spring clock change, the findings highlight how sensitive our brains can be to even small shifts in our daily rhythms. Most people adjust within a fortnight, but the darker commute that follows can affect mood and motivation right through the winter.

The effects you see at work are predictable: slower reaction times and more mistakes in the first hours of the day, a bigger afternoon dip, shorter tempers, and more people reporting that they feel groggy or sluggish. A smaller group will experience seasonal depression that goes well beyond a slump. The practical steps below can support better mood, but they don’t replace proper care for anyone experiencing persistent low mood or depression.

Five things a manager can change

1. Make morning light a mandatory part of the workday for your team. The single most useful intervention is 20 to 30 minutes of outdoor light early in the day, even when it’s grey. Overcast daylight is still many times brighter than a lit office. A walking meeting at 9am, a standing agreement that the first call of the day happens on a headset outdoors, or simply protecting the 15 minutes before people sit down will set a more active tempo for the whole day.

2. Schedule the difficult work for mid-morning. Alertness peaks a few hours after that first light. Put the work that needs judgement, creativity or careful attention between 10am and 1pm, and move routine admin and meetings that don’t need much from anyone into the afternoon dip.

3. Fix the lighting where people actually sit and work. If a desk is far from a window, a daylight-spectrum lamp used for the first hour of the morning helps. In the afternoon do the opposite: dimmer, warmer light from about 4pm, and screens turned down, so the brain gets a clear “evening” signal and sleep improves. Encourage blue-light filters or glasses for heavy screen work after lunch, as afternoon blue light disrupts the normal evening wind-down of our circadian rhythm.

4. Build in novelty. Winter days blur because the brain is getting the same low-contrast input every day. Small changes make a big difference: a new room for the weekly meeting, a different route in to the office, a new side project to work on for an hour. It sounds trivial, but the brain treats novelty as a signal to pay attention, and attention is the resource you’re short of in January.

5. Protect sleep, and say so out loud. Late emails, early starts and the midwinter social calendar all erode it. A manager who makes it clear that nobody is expected to reply after 7pm, and who keeps to that rule themselves, changes behaviour faster than any policy document. Consistent wake times matter more than total hours. Better sleep will have the biggest impact on productivity.

What about the gadgets?

I’m often asked about the light devices now sold for the home, from SAD lamps to the near-infrared helmets I work on as a scientific advisor to Neuronic. Bright-light therapy in the morning has a reasonable evidence base for helping with seasonal low mood. Near-infrared light to the brain has a well-understood mechanism and early, encouraging findings on attention, processing speed and sleep. None of it replaces the five steps above, however. Daylight, timing, sleep and a bit of novelty cost nothing and work for everyone.

The dark months are not a motivation problem. They’re a light problem. Address the root cause and watch the winter slump lighten up.

References

[1] Labarca G, Henriquez-Beltrán M, Sanhueza R, et al. (2024). Impact on health outcomes associated with changing the clock 1 hour during fall and spring transitions in the Southern Hemisphere. Journal of Clinical Sleep Medicine, 20(6), 887–893.