Q: Summer is a beautiful time of year, but sometimes I feel like people get more testy in hot weather. Is there anything to this, or is it just me? — Charlene A., Springfield, Ill.

A: You're not imagining things. Summertime out-of-sorts is a real phenomenon. And a recent study confirms that people are less likely to feel kindly toward others when they're hot.

Researchers did three different experiments, and all led to the same conclusion.

• First, they found that retail employees in an uncomfortably warm store were 50 percent less likely to do helpful things for customers compared with workers working in a comfortable temperature.

• A second experiment revealed that just the thought of being hot made people less likely to want to help others. The researchers paid people to take an online survey, but first they had half of them imagine a time they were uncomfortably hot. After the paid survey ended, they asked people to take an extra survey for no pay. A full 76 percent of people who had not imagined being hot were willing to take the extra survey, but only 34 percent of those who'd thought about being overheated were willing.

• In their last experiment, the authors found that 95 percent of college students in a cool room agreed to fill out a survey to benefit a local nonprofit, compared to 65 percent of those in a room heated to 80 degrees.

The researchers think that heat makes people more tired, and therefore less motivated to help others. We speculate that heat triggers an inflammatory response that boosts stress hormones, aggravates residual pains or ailments and amps up mood-altering hormones.

So if you find yourself getting hot under the collar this summer, take a minute to cool down, both physically and mentally. Be mindful of your mood and then be generous to others; they're hot too and could use a cooling act of kindness.

Q: My son's soccer coach is trying to improve the team by having them do what he calls vision drills. Does this stuff really make sense for a sports team? — Quentin H., Napa, Calif.

A: If done right, vision training is a smart move. To use it effectively though, your son's soccer coach should consult with a sports vision specialist so that each team member can be given vision tests. The tests can assess visual acuity, eye tracking, eye alignment and dominance, depth perception, processing speed and eye-hand coordination. That allows the eye doctor and coach to determine if an athlete needs targeted vision training to improve skills such as anticipating the trajectory of a bouncing ball, keeping track of what's happening peripherally or quickly changing focus from near to far objects and back again.

Sharpening up those abilities can really improve an athlete's performance. A new study in a European journal called Science and Medicine in Football looked at the visual prowess of Premier League soccer players. It found that not only did these elite athletes have superior vision skills, but players in different positions had unique strengths. For example, "Defensive players ... exhibit faster accommodative vergence [seeing how plays develop] than offensive players ..."

You see such visual superiority in the NBA, too. When Steph Curry brings the ball up court, he looks like he's staring off into space, but he sees everything through acute peripheral vision; plus he has sharp depth perception and unbelievable hand-eye coordination. (LeBron may be even better at this.)

In any sport, doing visual exercises can improve athletic performance. But it's also essential to make sure players' eyes are protected. As chair of the medical advisory committee of The United States Squash Racquets Association and former captain of the U.S. Squash team, Dr. Mike showed the USSRA Board pictures of eye injuries until they mandated protective goggles for squash matches.

So support your son's coach, Quentin, and let's all learn about the benefits of maintaining superior eye health.

Mehmet Oz, M.D. is host of "The Dr. Oz Show," and Mike Roizen, M.D. is Chief Wellness Officer and Chair of Wellness Institute at Cleveland Clinic. Email your health and wellness questions to youdocsdaily@sharecare.com.