We've heard the advice time and time again: In order for kids to heal from a concussion they need rest — lots and lots of rest. But a new study contradicts that age-old advice, suggesting that more may not be better when it comes to recovering from a concussion.

Most doctors recommend that kids who have suffered from a concussion rest for at least one to two days before returning to normal activities. Some extend that rest period out to a week. And when it comes to physical activities — the rest requirement is even longer. But until now there haven't been many studies or research to quantify just how much rest kids needs to recover from a concussion.

In a study from the Children’s Hospital of Wisconsin, researchers found that kids aged 11-22 who were prescribed strict rest for five days after a concussion actually reported more symptoms than those told to rest for one or two days. Stricter rest periods — such as using the cocoon method of recovery — also resulted in a slower recovery.

To be clear, none of the participants in this study were admitted to the hospital for their injuries. Rather, they were treated in an emergency room and sent home with recommendations from the staff to rest for a designated period of time.

For the study, lead researcher Danny G. Thomas, a pediatric emergency medicine doctor at Children’s Hospital of Wisconsin, and his team followed 88 young patients who were treated and released from the emergency department at Children's Hospital of Wisconsin for concussion. The patients were advised to rest for either no more than 48 hours or for five days. Each day, the patients rated their symptoms and took computer and paper tests to track their recovery. There was no difference between the two groups when it came to brain function and the ability to maintain balance. But the difference came in the patients' reported mental and physical symptoms.

Thomas reported that patients who were told to rest for longer periods complained of more physical symptoms like headaches and nausea in first few days, and more emotional symptoms such as anxiety, irritability and mood swings over time.

Researchers acknowledged that recovery from any ailment — particularly a concussion — may be different for each individual. And any return to activity that could result in another concussion should only happen after the patient has been given the OK by a doctor trained in concussion management. But they feel that their research confirms that resting for longer than 24 to 48 hours is not beneficial for most young patients and that the use of cocoon therapy, in which patients lie in a dark room for multiple days, should not be prescribed for younger patients.

A new study, however, finds that those first few minutes after a concussion really matter. Researchers discovered that high school athletes who kept playing right after a concussion ended up taking nearly twice as long to recover as those who immediately left the game. The study, published in the journal Pediatrics, tracked the symptoms of 69 teen athletes: 35 who were immediately removed from the game after receiving a concussion and 34 who kept playing. Researchers found that those who stayed in the game took an average of 44 days to recover, while those who left immediately after signs of concussion took an average of 22 days to recover.

Editor's note: This story was originally published in January 2015 and has been updated with new information.