"Moo-Q" asks people how positive or negative they are feeling at a certain time of the day.
It then records how well they perform in mental tests that measure processing speed and memory during the day, news.com.au reported.
"The app will alert you to changes in your brain over time, in memory or processing speed, and it can even help you to exercise your brain," Dr Sophie von Stumm from University of London was quoted as saying.
Normally, brain test scores are highest early in the day.
With this app, "you might be well advised to undertake important tasks that require a bit more brainpower first thing in the morning," Dr von Stumm said.
After undergoing the assessment tests, users can prepare personalised Moo-Q charts.
The chart displays a colour-coded graph showing mood and brainpower across hours, days and weeks.
"It is an old question in psychology if our brains work better when we are in high spirits, or if being a little miserable helps push our brains to maximum performance," Dr von Stumm said.
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