Seau was never listed as having a concussion in an official NFL injury report.
A doctor was treating Seau for orthopedic problems up until his death, the report said.
Seau had four current prescription medications in his home when he died: zolpidem, a sleep aid also known as Ambien; amoxicillin, an antibiotic; naproxen, a nonsteroidal anti-inflammatory drug used in over-the-counter medicines including Aleve; and propylthiouracil, a drug to treat people with overactive thyroid glands.
Of the drugs, zolpidem, which is addictive, was the only one known to cause possible changes in behavior, according to the National Institute of Health.
"(Some) people who took zolpidem got out of bed and drove their cars, prepared and ate food, had sex, made phone calls, were sleep-walking, or were involved in other activities while not fully awake," according to the NIH website. "After they woke up, these people were usually unable to remember what they had done."
Seau drank socially and did not smoke, nor did he have a history of illicit drug use, the report said.