A 24-hour ambulatory EEG is performed to check whether the patient has abnormal electrical waves issued from the brain during the day. Abnormal waves refer to epileptic waves, including sharp waves, spiking waves, spiking slow waves, spiking slow waves, and polyspiking slow waves. If the patient has epilepsy but is not in a seizure phase, a normal EEG may fall into the normal range or a mildly abnormal EEG that does not capture epileptic waves, but the patient has a higher rate of abnormal electrical brain discharges after falling asleep or when he/she is about to wake up. If a 24-hour ambulatory EEG is done, it is possible to capture abnormal waveforms during this time period. Even if the patient is not having a clinical seizure, there may be a positive result. When performing a 24-hour ambulatory EEG, the patient can also be instructed to perform actions that have the effect of inducing EEG emissions, such as hyperventilation and flash stimulation, which can increase the rate of positive findings.