Why mental load can be exhausting when you haven't moved all day.
Research on executive function shows that when overall cognitive demand is high, everyday tasks that are normally automatic start requiring noticeably more effort.
Study title: When Total Demand Is High, Even Small Tasks Feel Harder — Diamond, A., Annual Review of Psychology, 2011
- Study type
- Systematic review
- Population
- Mixed child, adolescent and adult samples across cognitive and developmental psychology research
- Published
- 2011
- Evidence confidence
- Strong confidence
The short version
A review of executive-function research concludes that planning, deciding, remembering and initiating draw on a shared, limited pool of resources. When total demand on that pool is high, performance on tasks that would normally feel easy measurably declines.
The finding, drawn out
- Anticipatingnoticing what will be needed
- Rememberingholding it until it's relevant
- Planningworking out how and when
- Decidingchoosing, often for other people
- Following upchecking it actually happened
A Selfey diagram illustrating the concept described in this review. Not a measurement, and not a claim about sequence in the brain.
Why it matters
It explains a specific and common experience: the day was not physically hard, and yet answering one more simple question feels impossible.
01
The question
02
How it was studied
03
What they found
04
Limitations
05
What it may mean
In real life
This lines up with the experience of everything — breakfast, replying to a text, getting dressed — feeling like 'one more task' on an overloaded day.
Try this
On an overloaded day, reduce your total list rather than organising it further, and complete one small task fully before adding anything new.
Evidence confidence
Strong confidence
This is a widely cited, thorough review of a large and consistent body of executive-function research, though it synthesises many different studies rather than presenting one single finding.
Source
Diamond, A. (2011). When Total Demand Is High, Even Small Tasks Feel Harder. Annual Review of Psychology.
Peer-reviewed · Free full text available · Last reviewed 2026-08-15
Read the original research →One study isn't the whole storyOne study gives us a piece of the picture. Selfey looks for patterns across the broader evidence rather than treating a single finding as a rule.
Read this in everyday terms
What to Do When Everything Feels Like Another TaskSelfey research briefs are educational summaries, not medical advice, diagnosis or treatment. Research describes patterns across groups; it cannot tell you what is right for your situation.
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