The current body of sports-related concussion literature has progressed over the years by investing time in much needed research, although research conducted on high school-aged athletes remains scarce. Accordingly, the present study sought to compare severity of reported symptoms pre- and post-concussion involving fatigue, trouble falling asleep, sleeping more than usual, sleeping less than usual, and drowsiness in male and female high school athletes. Participants included 64 males 43 females (N=107) who underwent baseline testing of their neuropsychological functioning prior to the beginning of their sports season. All participants sustained an in-season concussion and were serially reassessed approximately within three days or four days or more for their first measurement post-injury. If a second measurement was needed then 10 days or less or 11 days or more post-injury test results were acquired. Participants reported, no matter how many days had passed after a concussion, fatigue was a significant symptom. Participants also reported on post-concussion testing four days or more later that sleeping less than usual was less pronounced than their baseline symptoms. Similarly, the symptom continued to decrease when measured 10 days or less and 11 days or more post-concussion. A relationship between gender and drowsiness symptoms reported post-concussion was also evidenced. Females who sustained an in-season concussion reported increased drowsiness within three days of post concussion testing. Males also reported an increase in drowsiness after four days or more had passed post-concussion. The results of the present study suggest that a concussion may result in increased symptoms of fatigue and drowsiness and decreased symptoms of sleeplessness. There was also a gender component to concussions that caused increased drowsiness sooner in female athletes than in male athletes, although both genders suffered from an increase in this symptom. This research concludes that there are post-concussion symptoms related to sleep that may linger for several days before subsiding and relying solely on the athlete’s self report may not always be the most reliable source. The post-concussive symptoms are important for the parents, teachers, athletic trainers, coaches, anyone involved with the athlete to be aware of because sleeplessness, fatigue, and drowsiness can potentially cause concerns in other areas (e.g., inattention, intellectual performance, emotional changes, and behavioral disorders) that may be delayed beyond 10 days post-concussion.