The Tiredness That Isn’t About Sleep: Why Do I Feel Tired Suddenly?

Have you ever felt a tiredness so heavy no amount of caffeine can shift it? 

It isn’t a physical tiredness, it’s more like a grey cloud hanging over you, weighing down your mind so much that all you can think about is how long it is until bedtime. In fact, you may even consider a nap at your desk right here and now.

It comes out of nowhere, sometimes in the middle of the day. You’re fine one minute, then suddenly so exhausted that even the simplest task feels impossible.

When “tired” isn’t actually tired

I first noticed this years ago, long before I understood what it really was.  I often found myself wondering, “Why do I feel tired suddenly?” This wave of tiredness would hit me at work: before interviews, presentations, difficult conversations. It didn’t make sense at the time, I just assumed I was tired.

Then I noticed a pattern. This tiredness showed up before I was about to do something new, uncertain, or outside my comfort zone. The moment the task was finished, the tiredness disappeared and my energy would return.

That’s when I realised: this feeling isn’t really tiredness at all. It’s fear, resistance and discomfort showing up in disguise. Your brain senses something unfamiliar - a new challenge, a step forward, an opportunity - and instead of saying, “This feels uncomfortable” it sends a wave of tiredness. It’s your mind’s way of pulling you back into what feels predictable and safe.

It’s easy to mistake it for something else

Your brain prefers certainty. It loves the predictable, it loves keeping you in your comfort zone. And when you step outside that, it reacts with whatever it can: tiredness, distraction, procrastination. Anything to guide you back to what feels known.

You might wonder if it’s burnout or question where your motivation’s gone. But burnout drains you when you’ve been doing too much for too long, whereas this tiredness shows up before you’ve even started.

We often build new or uncomfortable tasks up in our heads. A ten-minute job suddenly feels huge, a simple conversation becomes a mountain and far more of a ‘thing’ than it really is. No wonder your energy drops, your brain is treating it like a threat.

And think how many times you’ve finally done the thing you were dreading and thought, “That wasn’t as bad as I imagined.” Sometimes you even wonder why you avoided it for so long, or even look forward to doing it again.

So how do you move through it?

When this shows up, try asking yourself:

“Am I truly tired… or am I uncomfortable because something matters here?”

Start by recognising what this feeling might really be. Look at what you have coming up and notice how your mind and body reacts as you think about each thing. It’s often the task you’ve quietly been avoiding, not the obvious one.

For example, I love my daily workouts, they’re something I genuinely look forward to, but I started noticing this heavy, sudden tiredness right before certain sessions. It made no sense. I wasn’t sleep-deprived, I wasn’t overtraining, and I wanted to be there.

Then I realised there was always one exercise programmed into those workouts that I found tougher than the rest. Not impossible, just uncomfortable. And even though I’m someone who enjoys pushing myself, that one movement was enough to trigger the cloud. As soon as I’d done that one exercise the tiredness would lift and I’d get on with the rest of the session.

It wasn’t physical fatigue, it was anticipation about what was to come. It was me pushing myself out of my comfort zone and my mind trying to fight it.

So look beyond the obvious. It might be something surprisingly small, and the solution might be simple.

Once you know what’s really going on, take one tiny step, something really small. Often once we start, we realise it’s not as hard as it seemed and the momentum builds. Before you know it you’ve done the thing you were so worried about.

Be kind to yourself. New things take energy. Take an intentional break if you need one. Maybe you just need to step away and come back with a clear head.

If this kind of tiredness sounds familiar, know that nothing’s wrong, this is all part of the process.

You’re simply doing something new and that takes energy.

Give yourself permission to pause, to breathe, and adjust if you need to. Every small step makes the next one easier and each time you move through it, you widen your comfort zone and strengthen your confidence.

You don’t need to have it all figured out. You just need to keep choosing to move forward in a way that feels right for you.

If you’d like more real-life reflections like this, head back to the blog page to keep reading.