If your mind has ever gone blank trying to remember exactly what day of the week you're living through, take comfort in the fact that this is now an officially recognised scientific phenomenon. And a new study has found that the problem is particularly bad on Tuesdays, Wednesdays, and Thursdays.

Because Mondays and Fridays are associated with the positive and negative feelings of the start and the end of the week, they tend to stick in our minds more readily. When it comes to the midweek monotony, however, people struggle to tell the days apart. Stress and excitement levels tend to balance out, making these the least memorable and most forgettable days of the week.

The study was led by psychologist David Ellis from the University of Lincoln in the UK, and involved a survey of close to 1,200 people. Participants were asked to submit a form indicating what day of the week it 'felt' like to them: Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday. They were also invited to suggest words associated with particular days, and the speed of their responses was noted as well.

"Midweek days are confusable because their mental representations are sparse and similar," explains the team's final report in PLoS ONE. "Mondays and Fridays are less confusable because their mental representations are rich and distinctive, forming two extremes along a continuum of change."

Negative words like "boring", "hectic", and "tired" were linked to Mondays, while Fridays brought up more positive associations like "party", "freedom", and "release". The researchers suggest that the more frequent use of these days in natural language - from stories to pop songs - is one reason why they have stronger links to particular feelings and associations.

Part of the study was run during a week that started with a public holiday, which seemed to confuse matters even further: a large proportion of the respondents said they felt a day behind, emphasising the importance of Mondays and Fridays as markers for the start and end of the week. In total, 40 percent of respondents confused the current day with the preceding or following day, and most of those mistakes were made midweek.

"The seven day weekly cycle is repeated for all of us from birth, and we believe this results in each day of the week acquiring its own character," says Ellis in a press release. "Indeed, more than a third of participants reported that the current day felt like a different day, and most of those feelings were on Tuesdays, Wednesdays and Thursdays, reflecting the midweek dip in associations attached to different days… Our research implies that time cycles can shape cognition even when they are socially constructed."

The research team now wants to use its findings to explore patterns in health and economics that fluctuate as the week progresses. The research data might also prove useful in psychological studies, the academics say