How Sleep Deprivation Affects Your Ability to Make Decisions at Work

You used to be the person people came to for answers.

The one who could weigh up a situation quickly, trust their instincts, make a call and move forward with confidence. The one who could hold ten things in their head at once and still spot the detail everyone else had missed. And now you are standing in the supermarket unable to decide between two types of bread. You are in a meeting and someone asks for your opinion and your mind goes completely blank. You are writing an email and you cannot work out if your tone is right, so you rewrite it four times and send it anyway hoping for the best.

This is not you losing your edge. This is sleep deprivation doing exactly what the research says it does to the decision making brain. And once you understand what is actually happening, it becomes a lot easier to stop blaming yourself for it.

What happens to your decision making brain when you are sleep deprived

The part of your brain most responsible for decision making is the prefrontal cortex. It handles everything from weighing up options and anticipating consequences to managing risk, regulating emotions and thinking creatively. It is essentially the part of your brain that makes you good at your job.

And it is the part of your brain that is most severely affected by sleep deprivation.

Research from the University of Pennsylvania found that even moderate sleep deprivation, defined as getting six hours or less per night, significantly impairs prefrontal cortex function. Participants in the study made poorer decisions, took longer to reach conclusions, were more likely to choose the riskier option and were less able to adapt when circumstances changed.

Perhaps most worryingly, the same research found that sleep deprived participants consistently underestimated how impaired they were. They thought they were performing fine. They were not.

The three types of decisions that suffer most

Not all decisions are equally affected by sleep deprivation, but three types in particular take a significant hit.

1) Complex decisions that require weighing up multiple factors are much harder when you are tired because your working memory, the mental workspace where you hold and manipulate information, is significantly reduced. You can hold fewer things in your head at once, which makes nuanced decision making feel overwhelming rather than straightforward.

2) Emotional decisions become harder because sleep deprivation increases activity in the amygdala, the part of your brain that processes threat and emotion, while simultaneously reducing the prefrontal cortex's ability to regulate it. This means you are more reactive, more likely to interpret neutral situations as threatening and more likely to make decisions driven by anxiety or irritability rather than clear thinking.

3) Fast decisions under pressure suffer because your processing speed slows significantly when you are sleep deprived. What used to feel like a quick, instinctive call now feels slow, uncertain and uncomfortable. And in a demanding job where fast, confident decisions are often required, this can feel absolutely crushing.

The confidence piece

Here is something the research does not always capture but that I hear from so many working mums. It is not just the quality of the decisions that changes. It is the confidence in making them.

When you are sleep deprived you second guess yourself more. You seek reassurance more. You hesitate where you used to act. And in a professional environment where confidence is often as important as competence, this can feel like a very public unravelling of something you worked very hard to build.

You are not less capable. You are less rested. Those are very different things.

What you can do right now

While the only real solution to sleep deprived decision making is more sleep, there are some practical things that can help in the short term.

Give yourself more time than usual for important decisions. Your processing speed is slower when you are tired so build in the extra time rather than fighting against it. Write things down rather than trying to hold them in your head. Your working memory is reduced so externalising information by writing lists, notes and summaries reduces the cognitive load significantly. Delay non urgent decisions to your sharpest time of day if you can. Most people have a window of better cognitive function even on broken sleep. Save the big calls for that window. Ask for input from colleagues you trust. This is not weakness. This is smart resource management when your own resources are temporarily depleted. And be honest with yourself about your limits. Pushing yourself to make high stakes decisions when you are severely sleep deprived increases the risk of errors that could have real professional consequences.

The bigger picture

Decision fatigue is a real phenomenon even in well rested people. The more decisions you make throughout the day the worse the quality of your later decisions becomes. For a sleep deprived working mum who is also making dozens of decisions about childcare, feeding, routines and household management before she even gets to her desk, this effect is amplified enormously.

You are not failing at your job. You are failing to get enough sleep. The solution to one is the solution to the other.

How I can help

I am Lottie, a Norland nanny with 10 years experience, 17 years in childcare altogether and OCN qualified through the Sleep Consultant Academy. I work with families across Gloucestershire, the Cotswolds and the whole of the UK, including so many working mums who came to me not just because their baby was not sleeping but because they could feel what it was doing to them professionally and personally.

My Night Night by Zoom package gives you a fully bespoke sleep plan, daily WhatsApp support and follow up calls over two to three weeks. And if you just need a focused hour to talk through what is going on, my Sleep MOT at £98 is the perfect place to start.

You built a career on your ability to think clearly, act decisively and show up as the best version of yourself. Sleep deprivation is borrowing against that. And the interest rate is brutal.

It is time to start paying it back. Book your free discovery call today and let us get your sleep, and your sharpness, back where they belong.