A study published in Science Advances from the University of Toronto Scarborough examined the productivity of individuals. 

The research tracked university students over 12 weeks to evaluate individual changes. 

A key player in this study is domain-general cognitive state or mental sharpness. 

This is a varying state of how clear, focused and efficient a person is at any given time. 

“Some days everything just clicks, and on other days it feels like you’re pushing through fog,” Cendri Hutcherson, associate professor of Psychology at the University of Toronto Scarborough, said in a news release. “What we wanted to understand was why that happens, and how much those mental ups and downs actually matter.”

The university students completed short daily tests that measured how quickly and accurately they could think. They also kept track of their mood, goals, productivity, sleep and workload. 

The purpose of collecting this data was to see if participants could make quicker decisions, concentrate more easily and follow through on tasks or determine whether simple activities felt difficult to them. 

The results of the study showed that when students were sharper than usual, they completed more of their goals and often aimed higher, especially with their academic work. 

The opposite occurred when their mental sharpness dropped. 

An important clarification is that results remained consistent regardless of an individual’s personality trait. For example, a person may have grit or self-control, which influenced their overall performance, but these traits did not alone prevent them from having less productive days. 

Therefore, “What we’re capturing is what separates those good days from the bad ones,” Hutcherson said. 

Mental sharpness has a drastic impact on productivity. 

Researchers estimated that being above or below the usual level of mental sharpness could shift productivity by about 30 to 40 minutes in a single day. The difference can average around 80 minutes of work between the best and worst days.

When students get more sleep than usual and earlier in the day, they tend to perform better. 

Mood can also impact mental sharpness. When an individual feels motivated and focused, they experience a boost in mental sharpness. On the other hand, depressive moods led to lower levels of it. 

This suggests that if people focus on specific combinations of emotional states, they may nurture greater mental sharpness.

Workload was found to have a mixed impact. Higher mental sharpness can be attained by putting in longer hours in a single day. 

However, the opposite was seen for extended periods of overwork: mental sharpness was lowered and individuals were less productive. 

“From our data, there are three things you could do to try to maximize mental sharpness: getting enough sleep, avoiding burnout over long periods of time, and finding ways to reduce depressive traps,” Hutcherson said. 

This study focused on students, but the insights could apply to broader groups. However, further study is needed to help people make more adaptive choices about how to work, as well as when and how to rest. 

The subjectivity of self-reported goal achievement can be overcome with passive digital trace data that tracks objective behavior such as physical activity, social engagement and daily work, eliminating causal inferences.