Feeling irritated, stressed, and finding it hard to get stuff done? You might have cognitive fatigue

By Ellen Scott, Lifestyle editor Saturday 9 Feb 2019 10:59 am Ever feel like your brain just isn’t working? The simplest task feels impossible, making any decision is unfeasible, and you feel strangely disconnected from everything that’s going on, as if you’re dreaming, or living in the middle of a dense fog. That probably sounds familiar. We know full well that stress levels are high and loads of us are on the brink of burnout. But what we’re talking about here isn’t a meltdown of catastrophic proportions or a reaction to overwhelming stress… it’s just a feeling that you’re trying to move through sludge.

What causes that feeling? Why does it happen? And what can you do to stop it? It’s often down to cognitive fatigue. Cognitive fatigue is, essentially, tiredness. Not physical tiredness, but mental exhaustion. It happens when we have to work with our minds for prolonged periods of time, whether it’s writing an article, figuring out a schedule, doing research, or reading a book. Essentially, any time your brain is busy, you’re building towards cognitive fatigue. When you reach cognitive fatigue, even the most basic mental task becomes a struggle.

Dr Catherine Huckle, clinical psychologist at the University of Surrey, tells ‘Cognitive fatigue happens when we have a number of demands on our thinking that go on for a sustained period. ‘The result is that we become less able to ignore distractions, we need more time to plan and our thinking becomes less flexible. We also become less able to carry out high level information processing (tasks that require us to absorb information, apply a process to the information and then deliver a transformed piece of information – tasks such as complicated maths problems).’ It makes sense when you ponder it – the same way your muscles would get tired if you ran around for hours, your brain struggles to keep going if you’re engaging it constantly. But, you might think, isn’t everyone’s brains constantly working? The answer to that is yes.

Signs you’re experiencing cognitive fatigue: You find it difficult to concentrate You’re forgetful You’re easily irritated Tasks that should be simple feel difficult You feel overwhelmed You’re struggling with sleep You have physical symptoms of stress such as headaches, tension, and an increased heart rate You feel disconnected from the world, like you’re in a dream or in a fog You experience a ‘mental block’ – when you simply can’t do any thinking Cognitive fatigue happens when that work becomes too much; when too much is packed into a short amount of time, when there’s pressure to do that work, and when you’re not making time to relax and unwind. ‘There are different theories as to the cause of cognitive fatigue,’ Dr Huckle explains. ‘Some researchers view cognitive fatigue as a result of reduced energy resources – the idea that your batteries are running out or that you can’t continue any longer. ‘There is suggestion that the number of tasks and the difficulty of tasks impacts on how quickly one becomes fatigued, but there is also strong evidence to suggest that the time that is given to get tasks done makes a difference. ‘So if you have some difficult tasks on your to-do list but a reasonable amount of time to do them you are less likely to experience cognitive fatigue than if you are time pressured. ‘There has also been discussion of the role of motivation and effort – that is, it feels difficult to keep going with a particular task because your preference is to be doing something else – resting, or other activities that are less demanding.

‘What we do know is that cognitive fatigue is a distinct phenomenon from sleepiness – in fact, research shows that as cognitive fatigue increases sleepiness is not affected. ‘One explanation of this is that, when a task is demanding, we have to keep all cylinders firing to manage, and the effort of this means we are wide awake (perhaps that experience of feeling “wired” when we are trying to get through a busy and demanding day).’ Overworking is an issue, of course, but a real problem occurs when we discount other forms of mental work and the impact they can have. We’re experiencing cognitive fatigue, and as a result, errand paralysis, because we tend to ignore the mental effort required for the non-work parts of life that can be just as draining. Think of life admin: having to remember plans, book in appointments, email people back, and clear our notifications.


These don’t feel like proper mental work because they’re not part of being in an office, but they add up and take their toll. When we dismiss the impact of life admin, we’re at risk of exhaustion, thinking we don’t need to rest up because we haven’t really been doing anything. (Picture: Ella Byworth for Comparison makes things worse – we look at everything other people are doing and feel that we should be doing the same. But in reality, there are hidden factors that impact our capacity to handle our cognitive load. Mental or physical health issues run down our mental battery, making a heavy cognitive load feel that much heavier. ‘As well as inherent individual differences, capacity can be affected by a number of neurological conditions,’ Dr Huckle tells us. ‘It also makes sense that if we have a high level of cognitive load on an everyday basis (perhaps we have to keep in mind a number of responsibilities and appointments, such as those associated with childcare or caring for someone) it will take less demands to invoke cognitive fatigue. ‘Even concerted efforts towards breaking a habit (such as smoking) or adhering to a new resolution (think exercise or dieting) – anything that requires willpower – increases cognitive load and makes us more susceptible to cognitive fatigue.’ So let’s say you’re more prone to cognitive fatigue, whether due to the demands of your job, the level of life admin you have to undertake, or because you have an illness that impacts your capacity to handle your cognitive load – what can you do about it? The first step is recognising that cognitive fatigue is real and valid. Don’t allow yourself to feel like failure for struggling, or think you can just ‘power through’. You can’t. We all need to make time to fully unwind with an activity that lets us stop our minds working on overdrive. That may be meditation and yoga, or it can be as simple as watching mindless TV and playing with a pet. MORE: HEALTH Mum says breast milk helped fade her stretch marks Boy, 6, left in coma after being sent home from school with headache Women tell us what a smear test actually feels like Sorry, but the order you drink different booze doesn’t make a difference to your hangover It’s also vital to reevaluate our lifestyles. Our current emphasis on productivity and hustling means that we’re overloading our minds and failing to cater to our own needs.

Dr Huckle advises: ‘Strategies might include cutting back on the number of tasks that you are trying to achieve, increasing the timeframe in which you aim to get things done or lowering your standards (accepting a lesser performance and saving your best for when it is absolutely essential). ‘It can also help to feel more in control, which can be achieved through planning and scheduling of tasks, delegating where possible and by being assertive about what you can and cannot take on.

‘Organisations can help their staff to achieve this through encouragement of regular breaks, shorter working days and flexitime. ‘There is also some thinking to be done in terms of the satisfaction of everyday tasks – if tasks are interesting and enjoyable (and even if they are still demanding and time pressured) they are less likely to cause cognitive fatigue.’ It’s vital to look after yourself to ensure that when your cognitive load increases, you won’t collapse underneath it. That means sleeping and eating well, talking through your feelings, and asking for help when you need it. You shouldn’t have to put up with feeling in a fog, with being irritable, forgetful, and struggling to do things you actually care about. A feeling of total overwhelm cannot and should not be our basic state. Take cognitive fatigue seriously, and give yourself a damn break.