We spend a lot of time in meetings. In fact, Americans alone hold a whooping 11 million meetings per day. That comes out to 55 million meetings per week and 220 million meetings per year.

The problem, however, is that many meetings are unproductive. That’s because attendees are multitasking, daydreaming, or dozing off. That’s wasting both valuable time and money — some have found that unproductive meetings cost more than $37 billion per year.

Fortunately, you can correct this problem by using the following eight science-backed strategies for having more productive meetings.

1. Set meetings for 15 minutes or shorter.

The average meeting length is 31 to 60 minutes. And that’s way too long. The reason? We just don’t have the attention spans.

That’s why TED Talks do not go over the 18-minute mark. As TED curator Chris Anderson explains, “It [18 minutes] is long enough to be serious and short enough to hold people’s attention.”

Furthermore, consuming too much information is draining on your brain — even if you’re just listening to someone speak. It’s also been found that we retain more information when receiving it in shorter amounts of time.

The good news is that you can adjust your meeting. If you have a hectic day then schedule a 10-minute meeting. If you need a couple of extra minutes to explain a project then block out 20-minutes. Just remember to keep your meetings as short as possible.

2. Invite fewer people.

Jeff Bezos has something called a “two-pizza rule.” I wish this meant that all meetings should include pizza, but it really means that if your team can’t be fed with two pizzas, it was too big. This is how Bezos is able to keep meetings productive — only inviting essential stakeholders.

This isn’t exactly a new concept. In 1957 British naval historian C. Northcote Parkinson came-up with Parkinson’s law of triviality. This law argues that groups of people often give disproportionate weight to pointless discussions.

More recently, research has found that when there is too much data from too many people it can be disabling.

So instead of inviting your entire team to the meeting, only include those who absolutely have to be in attendance.

3. Provide ample refreshments.

Having refreshments isn’t just a nice perk for attendees. They can also make your meetings more productive.

Dehydration, for instance, can impact the brain’s cognitive function. This decreases the ability to concentrate and carry out basic tasks. As such, you should make sure that everyone in the meeting has plenty to drink — preferably water. You can also provide coffee, tea, and fruit or vegetable juice but make to lighten up on the sugar and cream.

As for food, stick with fruits and vegetables, nuts, granola, yogurt, or wraps made from whole-grain tortillas and lean deli meat like turkey.

4. Perfect your presentation.

I’m sure we’ve all been in a meeting where we just listen to someone speak for an hour. If we’re lucky they may have a PowerPoint to break-up the monotony. However, it’s a boring meeting that causes us to zone out and forget everything that was discussed.

You can change that by making sure that your presentations are pitch-perfect by:

  • Following the rule of 3. Studies have found that we’re only able to absorb three to seven points during the short term. So the next time you schedule your meeting package your key messages into groups of three, such as “your three objectives.”
  • Using the right colors. Different colors make people feel differently. For example, red stimulates excitement, while blue sparks creativity. Use the right colors you want your audience to identify with you and your message in your attire, handouts, and PowerPoint Presentation.
  • Telling a story. “Data, while necessary, can be boring,” says Rick Lozano, a corporate trainer, and keynote speaker. “Human beings are wired for storytelling. What story can we tell that makes these numbers come to life? If we can connect to their journey, their experience, they might be more likely to listen.”

5. Schedule meetings for Tuesday afternoons.

I know that it’s common to hold a meeting on a Monday morning. After all, it gives you and your team a chance to plan and prep for the week. However, it’s been found that the best time to hold a meeting is on Tuesday afternoon.

From Quartz:

“If you want to make sure everyone can be there, the best time to meet is Tuesday afternoon, according to a study from YouCanBookMe, a UK company that makes scheduling apps for businesses. The firm crunched data from more than 2 million responses to 530,000 invitations and concluded that 2:30 pm Tuesday is the time most people are free.”

However, Bridget Harris, co-founder of YouCanBookMe, stated that the company holds a weekly meeting at 3 pm every Wednesday. “By Wednesday lunchtime, they’ve had two days to try and figure out what they’re trying to do,” said Harris.

Regardless if you schedule a meeting on Tuesday or Wednesday, you don’t want to schedule them too late in the afternoon since everyone is run down at this point. At the same time, you don’t want to schedule meetings late in the afternoon or on Friday when people are run down.

6. Ask everyone to stand-up.

Ditch the chairs and encourage everyone to stand-up — or go for a walk. Andrew Knight and Markus Baer of Washington University conducted a study on stand-up meetings versus sit-down meetings that found that standing up allows for greater collaboration and more excitement regarding the creative process.

Best of all? Stand-up meetings can be “daily scrum,” (a rugby play) a “daily huddle,” (football) or “morning roll-call” where the entire team receives a brief status update.

7. Encourage everyone to take handwritten notes.

It makes sense for attendees to either leave their electronic devices elsewhere or turn then off before attending a meeting. You don’t want everyone to be distracted by emails or other work. But, how can your team take notes?

Let them go old school and actually write notes down.

UCLA has found that provides eliminating distractions, handwritten notes help us better understand concepts and remember information later on.

8. Keep your audience engaged.

Finally, you want to keep your audience engaged throughout the meeting.

One way to accomplish this is by making sure that the meeting is necessary and has a clear purpose. You can ask attendees “What exactly are we meeting about?” at the start of every morning to make sure this is the case. Just make sure that their answers are five words or less. If everyone is on the same page and knows what the meeting is about, they want to get lost or confused.

Additionally, you want to be authentic, humorous, avoid using jargon, provide handouts, and allow for discussions at the end.