Why Wasn’t I Productive Today?

Quick answer: Most unproductive days have a cause you can name, usually short sleep over several nights, stress that hasn’t worn off, a morning broken up by switching between tasks, or a task too vague to start. They’re hard to spot on the day because sleep loss in particular makes you worse at your work without making you feel much worse. Two weeks of simple notes will usually show you which one is yours.

There’s a particular kind of annoyance kept for the bad day that turns up after you’ve done everything right. Your tasks are in Todoist and the week is blocked out in Google Calendar, and yet by three on Tuesday you’ve read the same paragraph of a brief four times, opened the Q4 plan and closed it again, and made a cup of tea you didn’t want. By five you’re wondering whether it’s the system that’s broken or you.

Usually it’s neither. A good task manager is built to tell you what to do and in what order, and most of them do that well. What none of them can tell you is the state you’re in when you sit down to do it, and that’s normally the thing that shifted between Monday and Tuesday. Ask yourself what was different about today and there’s nearly always an answer, and quite often there are two or three piled on top of each other.

Your to-do list has no idea how you slept

Todoist knows about every deadline you’ve set and Google Calendar knows about every meeting you’ve accepted. Neither has any way of knowing that you got five and a half hours last night, that your HRV has been drifting down since Saturday, or that breakfast involved a difficult conversation. Energy apps such as Rise have the reverse problem: they’ve studied your sleep closely and have never once seen your task list.

So each morning you do the joining up yourself, by feel. That works fine on a normal day and lets you down on the off days, because a tired brain is a poor judge of how tired it is, which is where sleep comes in.

The usual suspects

Plenty of things can spoil a working day, but for people doing thinking work a small number account for most of it, and the hard part is noticing them while they’re happening.

Short sleep, several nights running

I know, sleep. It’s on this list because it keeps turning out to be right. In a study at the University of Pennsylvania, people kept to six hours a night for two weeks ended up with attention lapses about as bad as people who had gone two whole nights without any sleep (Van Dongen et al., 2003). The part I find more useful is what happened to how they felt. Their sleepiness ratings crept up over the first few days and then more or less levelled off, while their performance carried on getting worse. They got used to feeling tired and lost track of how impaired they were, so by the Thursday of a short-sleep week, sleep doesn’t feel like the explanation even when it is. Our piece on sleep debt and productivity goes into how that debt builds.

Stress that hasn’t worn off yet

A tense meeting at nine, or a row at home before the school run, can take your planning brain offline for the rest of the morning. Amy Arnsten’s research at Yale shows that even fairly mild stress, if it feels out of your control, quickly weakens the prefrontal cortex, the part of the brain that plans, prioritises and keeps several things in mind at once, and hands more control to quicker, more reactive circuits (Arnsten, 2009). That’s how you can get through forty emails after a bad start and still not manage a single paragraph of the strategy doc. It’s also part of the reason eat the frog is the wrong call on some mornings. A walk will usually bring you back sooner than another hour in front of the blank page.

A morning chopped into pieces

Some days start perfectly well and then get sliced up. Sophie Leroy, who coined the term attention residue, found that when you leave a task unfinished to go and do something else, part of your attention stays behind with the first one and your performance on the second suffers (Leroy, 2009). Four meetings with fifteen minutes between each, or Slack going off every time you get into a sentence, can keep you busy from nine till six without you being properly on anything at any point. Unlike the other causes here, this one shows up in your calendar rather than your body, so you can often see it coming the night before.

A task with no obvious first step

If you’re perfectly capable of the work but can’t get yourself to start it, have a look at how you wrote it down. Edwin Locke and Gary Latham spent decades on goal-setting research and kept finding that specific goals lead to better performance than a vague instruction to do your best (Locke and Latham, 2002). A task that just says “Q4 plan” leaves you to work out where to begin before you can begin. Rewrite it as “draft three options for the Q4 budget” and you at least know what the first ten minutes look like.

Where you are in your cycle

Hormones shift across the month, and for many people the way they think and work shifts with them. A UCL study of 241 women found that during their period participants reacted faster and made fewer errors, while in the luteal phase, the roughly two weeks before a period, their reaction times were measurably slower (Ronca et al., 2024). The detail worth holding on to is that participants felt worse on their period and expected to do worse, when they were in fact at their sharpest. Add the poorer sleep many people get in the days before a period (Baker and Driver, 2007) and your cycle can change the shape of a working day without ever being the thing you’d think to blame. It varies a lot between people, so your own notes will tell you more than a general rule.

“But I already know when I work best”

If you’re reading a post like this, you probably have a decent sense of your own rhythm: whether you’re sharper first thing, and roughly when the afternoon slump turns up. That’s worth knowing, but it describes your average day, and the day that goes wrong is exactly the one that doesn’t behave like the average. The warning signs were often there by seven in the morning, in a short night, an HRV reading below your usual or a calendar without two free hours side by side.

Two weeks and a note on your phone

You don’t need a new app for this, only a fortnight and the notes app you already have. At the end of each working day, give it a score out of 5 for how much of the important work got done, and next to the score jot down:

• how long you slept the night before (from your wearable, if you wear one)
• anything stressful before or during the day
• your longest run of uninterrupted time
• your cycle day, if that’s relevant to you

When the two weeks are up, pull out your three or four worst days and look at what they share. Most people find one or two things that keep coming back, and they’re often not what they’d have guessed at the start. A few bad days won’t match anything at all, which is normal and no reason to rebuild your whole set-up.

How to use this with Phase

Phase does this reading for you every morning. It connects to the wearable you already have, whether that’s an Apple Watch, Garmin, Oura or WHOOP, and to your task manager (Todoist, Notion, Linear, Asana, Trello or Google Tasks) and Google Calendar. Phase ignores your readiness score. It works from the data underneath it, including sleep duration, sleep efficiency, HRV and cycle phase, and builds a cognitive profile for the day across six strengths: energy, motivation, focus, reflection, communication and creativity.

It then sets that profile against the tasks and meetings you already have and gives your plan an alignment score, which tells you how well today’s work fits the state you’re in. After three short nights in a row, for example, Phase will suggest pushing the hardest thinking later in the week and pulling forward the work a tired brain can still do well, so you know what sort of day you’re dealing with by nine o’clock rather than finding out at eleven.

Next time Tuesday goes nowhere

When a system you’ve built carefully still hands you a bad day, the cause is usually a change in you that the system couldn’t see. Work out what that change was a few times over and you’ll start to notice it coming, which makes planning around it a lot easier. There’s more on planning your day around the person doing the work in our focus and planning guides.

Join the waitlist at phaseforwork.com and be first in when Phase opens up.

The information in this post is for educational purposes only and does not constitute medical advice. Phase content on health, hormones, and bio data is reviewed by our clinical advisory team. If you have concerns about your health or wellbeing, please consult a qualified healthcare professional.