You’ve got a full hour until your next meeting. But you probably won’t make the most of that time, new research suggests.

In a series of eight studies, both in the lab and real life, researchers found that free time seems shorter to people when it comes before a task or appointment on their calendar.

“We seem to take a mental tax out of our time right before an appointment,” said Selin Malkoc, co-author of the study and associate professor of marketing at The Ohio State University’s Fisher College of Business

“We figure something might come up, we might need some extra time, even when there’s no need to do that. As a result, we do less with the available time.”

The study appears online in the Journal of Consumer Research.

In an online study of 198 people, Malkoc and her colleagues asked some participants to imagine they had a friend coming over to visit in one hour and “you are all ready for your friend to come by.” The others were told that they had no plans for the evening.

All participants were asked how many minutes “objectively” they could spend reading during the next hour and how many minutes they “subjectively” felt like they could spend reading during that same hour.

“Regardless of whether they had a friend coming by or not, participants said that they objectively had about 50 minutes available to read,” Malkoc said.

“That’s an amazing finding right there. Most people didn’t think even objectively they had a full hour to read. People are putting a little ‘just-in-case’ time into their schedules when there is no real reason to do that.”

When they were asked how much time they felt they had to read – the subjective measurement – those with a friend coming by felt that they had 10 more minutes missing in their hour – about 40 minutes.

The results held up in real-life studies as well.

The researchers asked participants recruited online to provide their actual schedules for the next day. Participants indicated when each scheduled task on their calendar would begin and how much time they would need before each task to prepare.