It’s Not “Just Stress”: A Real-World Guide for Managers Dealing with Sick Leave and Performance
If you feel like half your job is now sickness meetings, stress conversations and performance worries, you’re not imagining it.
In 2022/23, an estimated 875,000 workers in Great Britain were suffering from work-related stress, depression or anxiety, leading to 17.1 million working days lost. Stress, depression and anxiety made up 49% of all work-related ill health and 54% of all days lost to work-related ill health.
CIPD’s latest health and wellbeing data backs this up: mental ill health is now the top cause of long-term absence and a major driver of short-term absence too.
So if you’re trying to juggle patient demand, targets, rota gaps and then someone goes off with “stress”, you’re not alone – and you’re not failing. The system is under pressure, and managers are feeling it.
This matters because:
For the individual, unmanaged stress increases the risk of anxiety, depression, cardiovascular issues, sleep problems and burnout.
Under the Equality Act 2010, long-term mental health conditions (for example, depression or anxiety lasting 12 months or more and substantially affecting daily life) may be classed as a disability, triggering duties around reasonable adjustments.
For the organisation, stress-related absence drives up costs, impacts safety and quality, and quietly erodes team morale and retention. Stress is now a major cause of both short- and long-term absence across UK employers.
No wonder it feels complicated.
Why Managing Stress and Sick Leave Feels So Complicated
Here’s why most managers feel stuck:
Stress can be work-related, personal, or a blend of both.
You can see performance issues, but you’re also worried about pushing someone who is genuinely unwell.
You’re trying to be compassionate, while also running a safe and functioning service.
Fit notes sometimes say “may be fit for work if…” and no one is clear what that actually looks like operationally.
You’re worried about saying the wrong thing and ending up in a grievance, appeal, or worse.
I’m seeing more of this than ever – across Primary Care and growing SMEs – because life outside work is more stressful, workloads inside work are heavier, and the boundary between the two is thinner than it has ever been.
So let’s break it down into four different situations that often get muddled together.
1. Work-Related Stress and Sickness Absence
What it looks like
The fit note clearly references “work-related stress”.
The employee talks about workload, management style, conflict, bullying or workplace change.
There’s a clear link between the role and their symptoms.
This is where your organisation has a duty to look at the work environment, not just the individual. HSE data consistently shows workload pressures and lack of managerial support as key causes of work-related stress.
What “good” looks like
A welfare meeting early on (not weeks into the absence).
A stress risk assessment focused on work factors – not just a general chat about “how are you feeling?”.
Exploration of realistic adjustments (workload, priorities, supervision, breaks, rota, location etc).
Agreeing what is expected from both sides: what the organisation will do, what the employee is responsible for.
2. Personal Stress and Sickness Absence
What it looks like
The stress is primarily triggered by home, caring responsibilities, finances, relationships, health issues.
Work might be “okay” but they do not have capacity to cope with both.
Here, your duty of care is still real, even if the root cause is not work.
What “good” looks like
A welfare meeting that validates the reality of what they are carrying.
Exploring whether work can be a stable, predictable anchor rather than an additional stressor.
Signposting to support (EAP, GP, charities, debt advice, carers’ support) where available.
Looking at temporary, clear adjustments – for example, short-term lighter duties, some home working (if feasible), or a predictable pattern that helps.
You’re not expected to fix their whole life. But you are expected to handle the work side fairly and thoughtfully.
3. Performance Issues Driven by Stress
This is the knotty bit…
What it looks like
Work is slipping: errors, missed deadlines, emotional reactions, withdrawal.
There may be an illness, but there has also been a long pattern of avoidant behaviour, resistance to feedback or ongoing low performance.
You can feel compassion and frustration at the same time.
What “good” looks like
You do not park performance indefinitely “because they’re stressed”.
You do not rush to formal capability without understanding whether stress is a key driver.
You use a combined approach:
Support + adjustments where appropriate.
Clear performance expectations and examples.
Regular check-ins and documented conversations.
You involve HR or a legal professional to help you separate “can’t” from “won’t” and to ensure any formal route is fair and proportionate.
Stress does not give anyone a free pass on core role requirements – but it absolutely shapes how you support them to meet those requirements.
4. When Workplace Stressors Are Exacerbating an Existing Condition
Sometimes:
The person has a long-term mental health condition or neurodivergence.
Workload, change or conflict is making it worse, even if work isn’t the pure root cause.
Here, Equality Act duties are very likely engaged. Mental ill health is now one of the main reasons employees meet the legal definition of disability in the workplace.
What “good” looks like
Considering reasonable adjustments seriously (not as a tick-box exercise).
Recognising that “fairness” is not always identical treatment.
Using HR and, where helpful, Occupational Health to sense-check what’s reasonable.
Being prepared to tweak duties, structure, environment or supervision to keep a skilled person safely in work.
Return to Work: No Half-In, Half-Out
A safe, planned return to work is essential – for them and for you.
What causes chaos is the “half-in, half-out” approach:
someone is technically signed off, pops in anyway when they are feeling 95%, does 95% of the job, and everyone quietly pretends that the GP note and the risk don’t exist.
A better approach is:
Welfare / pre–return meeting
Understand current capacity: symptoms, triggers, energy levels.
Talk through what “a safe return” means in their role.
Be honest about what can and cannot be adjusted.
Finally, understand from the employee whether they feel 100% fit for work - anything less leaves you both exposed.
Respect the fit note
If the GP says “may be fit for work if adjusted duties are in place”, you have three options:Put the adjustments in place and monitor.
Agree a different, safe temporary role or duties.
Keep them off sick if safe work genuinely is not possible.
What you shouldn’t do is ignore the note and let them drift back into full duties without structure or support.
Use Occupational Health wisely
OH can give a clinical view of fitness and recommend adjustments.
But it is guidance, not a substitute for managerial judgement or operational reality.
Pair this with a more operationally focused stress risk assessment.
Only sign off full duties when they are genuinely fit to perform them
In safety-critical roles especially, “almost fine” is not good enough. They should either:be fully fit (100%) to do the core duties safely and consistently, or
be 100% fit to return on a clearly defined, temporary adjusted plan that is monitored and time-bound.
Welfare Meetings, OH and Job Responsibility Analysis
If you’re unsure whether someone can realistically do the role anymore, consider a structured approach:
Welfare meeting
Create space to talk about:what they can do now
what they cannot do
what would help
what feels unsustainable
Occupational Health referral (where it adds value)
Ask specific questions:Fitness for core duties
Likely prognosis and timescales
Suggested adjustments or restrictions
Whether the condition may be considered a disability
Job responsibility analysis
Step back and ask:What are the non-negotiable elements of this role?
Which parts can we tweak, share or re-order?
Are there alternative roles or configurations we should consider?
This is where it often helps to have an external HR partner who isn’t emotionally embedded in the case.
Why I Use Stress Risk Assessments Before Sending People to OH
At Thrive. HR UK, I use structured stress risk assessments based on HSE principles to work directly with staff and managers.
In an organisation employing over 200 staff, redesigning the process reduced the need for Occupational Health involvement by around 70%, cut costs, and improved retention by 16%. That happened because we stopped treating stress as a vague feeling and started treating it as a set of risk factors we could do something about.
Here is how the Thrive approach helps:
We sit down with the employee (and sometimes their manager) and break the situation into work and non-work factors.
We use a structured risk assessment to identify:
workload issues
role clarity problems
relationship or culture factors
control, support and change pressures
You then receive a clear, prioritised action plan that separates:
Must-dos (legal/safety critical)
Strongly advised (good practice, risk-reducing)
Nice-to-have options
This often gives a safer, more human and more targeted route than a generic OH referral where the employee tells their story again and gets a standard report that everyone struggles to implement.
Staff usually feel:
Heard and understood, not processed.
More confident that their manager and HR get it.
More willing to return, because the plan feels tangible, not theoretical.
OH still has an important role, especially for diagnosis, prognosis and complex conditions – but for many stress cases, a robust stress risk assessment is the better first step.
You Can Be Compassionate AND Clear
If you only take three things from this:
Stress-related absence is common – you are not the only manager stuck in this.
The numbers show this is a systemic issue, not a single “difficult employee”.Your job is to be both human and boundaried.
That means:listening
documenting
adjusting where reasonable
and still being clear about what the role needs.
You do not have to work this out alone.
At Thrive. HR UK, I help managers and leaders:untangle stress, sickness and performance
run meaningful stress risk assessments
design return-to-work and adjustment plans that are fair, legally safe and actually workable in real life.
If you’ve got a case right now that feels sticky, heavy or heading towards formal action, let’s fix it before it becomes expensive.
You don’t have to carry this alone. Email me today at rosie@thrive-hr.uk
Rosie Campbell LLM CIPD
Employment Law & People Risk Specialist
