As autumn draws on and winter is on the horizon, many employers focus on easy-to-spot seasonal hazards such as icy conditions, poor weather and increased driving risks. However, an often-overlooked health and safety concern is the effect that reduced daylight can have on employees’ mental wellbeing and workplace performance. Now that the clocks have gone back, this will mean lighter mornings for a while, but the evenings will be darker, and this will soon extend to late afternoon as well.
Seasonal Affective Disorder (SAD) and other seasonal mood changes can affect concentration, alertness and decision-making, creating additional workplace risks that employers should not ignore. For organisations whose operations are safety-critical, understanding and managing these risks can form an important part of a broader health and safety strategy.
What is Seasonal Affective Disorder?
This is a type of depression that follows a seasonal pattern, typically emerging during the autumn and winter months when daylight hours decrease. The exact cause of SAD is not fully understood, but it is thought to be linked to lower light levels that may affect the brain’s production of melatonin (which influences sleepiness) and serotonin (which helps regulate mood, appetite and sleep). They may also disrupt the body’s internal clock (circadian rhythm), affecting normal sleep–wake patterns. Symptoms can vary between individuals but commonly include:
- Persistent low mood
- Fatigue and low energy
- Difficulty concentrating
- Increased sleepiness
- Reduced motivation
- Feelings of irritability or withdrawal
Not everyone who experiences seasonal mood changes will have a clinical diagnosis of SAD, but even milder symptoms can have an effect on workplace performance and safety.
The Health and Safety Executive (HSE) recognises that mental health and wellbeing are workplace health issues and that employers have responsibilities to assess and manage risks that may affect employees’ health, including those linked to stress, depression and mental wellbeing.
Reduced concentration and alertness
One of the most significant workplace effects of SAD is reduced cognitive performance. Employees experiencing fatigue, low mood or disrupted sleep patterns may find it more difficult to:
- Remain focused on tasks
- Process information quickly
- Retain important information
- Maintain vigilance during repetitive work
- Make effective decisions under pressure
These challenges are not limited to physically demanding roles. Office-based employees may be more likely to make administrative errors, overlook important communications, misinterpret information or make poor decisions.
Research and guidance relating to fatigue and mental wellbeing consistently identify reduced concentration, slower reactions and impaired judgement as factors that can increase operational risk and human error. Similar risks are recognised by the HSE in relation to fatigue and workplace performance.
Increased risk of mistakes and accidents
A big factor in many workplace incidents is human error. When concentration and alertness decline, the likelihood of mistakes naturally increases. During the darker months, organisations may therefore experience:
- Increased near misses
- Data-entry and administrative errors
- Safety procedure failures
- Driving incidents
- Equipment misuse
- Reduced situational awareness
In lower-risk environments, this may result in productivity losses, customer service issues or compliance failures. In higher-risk settings, however, the consequences can be far more serious. Employees who are tired, distracted or struggling with their mental wellbeing may be less able to identify hazards, follow safe systems of work or react appropriately to unexpected situations.
Although SAD itself may not be the direct cause of an incident, the underlying effects on concentration, memory and alertness can contribute to a higher likelihood of accidents.
Particular concerns in safety-critical roles
The risks become especially important where employees perform safety-critical duties. Roles that may be particularly affected include:
- Drivers and fleet operators
- Construction workers
- Manufacturing and production staff
- Logistics and warehouse personnel
- Engineering and maintenance teams
- Healthcare workers
- Utilities and infrastructure workers
- Employees operating machinery or plant
These roles often require sustained vigilance, quick reaction times and precise decision-making. A momentary lapse in concentration when operating machinery, working at height, driving a vehicle or managing hazardous equipment can have serious consequences not only for the employee involved but also for colleagues, customers and members of the public.
Employers should therefore consider seasonal wellbeing factors as part of their wider risk assessment process, particularly where work activities already involve elevated levels of risk.
What does the law say about SAD?
Employers have a number of legal duties that may be relevant when considering the effect of SAD and reduced mental wellbeing.
The Health and Safety at Work etc. Act 1974 places a duty on employers to ensure, so far as is reasonably practicable, the health, safety and welfare of employees (amongst others).
The Management of Health and Safety at Work Regulations 1999 require employers to carry out suitable and sufficient risk assessments and implement preventative and protective measures where hazards are identified.
The HSE also makes clear that work-related stress and mental health risks should be managed in the same way as other workplace health and safety risks. Where mental wellbeing issues are foreseeable and could affect employee health or safe performance at work, employers should consider whether appropriate controls are in place.
In some circumstances, where an employee’s condition amounts to a disability, employers may also have obligations under the Equality Act 2010 to make reasonable adjustments.
Supporting employees through the winter months
Fortunately, there are several practical steps employers can take to reduce the effect of seasonal wellbeing challenges.
Improve workplace lighting
Poor lighting can contribute to feelings of fatigue and low mood. Therefore, businesses should consider:
- Maximising natural daylight where possible
- Reviewing workplace lighting levels
- Ensuring workstations are positioned to make best use of natural light
- Upgrading outdated lighting systems where necessary
While just using lighting will not eliminate SAD, it can help create a more comfortable working environment during darker months.
Encourage flexible working
Flexible working arrangements may help employees better manage their health and wellbeing. Examples include:
- Adjusted start and finish times
- Hybrid working arrangements
- Flexible break schedules
- Reduced commuting during darkness where operationally possible
Promote wellbeing initiatives
Employers should also ensure employees know where support is available. Creating an environment where employees feel comfortable discussing wellbeing concerns can help identify problems before they develop into more serious issues.
Practical measures may include:
- Employee Assistance Programmes (EAPs)
- Mental health first aiders
- Wellbeing awareness campaigns
- Training for managers to help them recognise signs of mental ill health
- Regular wellbeing check-ins
Review risk assessments
For safety-critical operations, employers may wish to review existing risk assessments during autumn and winter months. Questions to consider include:
- Are there roles where reduced alertness could increase safety risks?
- Are fatigue controls still appropriate?
- Do supervisors know how to identify potential wellbeing concerns?
- Are workloads realistic during seasonal pressure periods?
Wellbeing hacks
| Category | Recommended Adjustment / Control Measure |
| Environmental Light | Move workspaces closer to natural light windows. Review internal building layouts to maximise existing daylight. |
| Flexible Hours | Allow later start or earlier finish times so employees can travel and commute during daylight hours rather than pitch-black mornings/evenings. |
| Shift Planning & Breaks | Encourage short daylight breaks (such as an outdoor walk at lunchtime) to naturally regulate circadian rhythms. |
| Workload Management | Restructure non-urgent deadlines during peak symptom months (typically December through February). |
| Safety-Critical Roles | Temporarily reassign or adjust duties for those suffering severe concentration drops who operate heavy machinery or transport vehicles. |
