What is the reason for the headache, nausea and vomiting after sleeping for a long time? There are several possible reasons for the above phenomenon: the first reason is that the patient may have high blood pressure, the most common symptoms of high blood pressure is to cause headache, nausea and vomiting. The second reason is that the patient may have Meniere’s disease, or vertigo syndrome, which can be triggered by some people when they wake up due to excessive sleep. The third reason is whether there may be some plant nerve dysfunction, especially during sleep, when nightmares can lead to sympathetic excitation, such as increased blood pressure, rapid heart rate, headache, and in severe cases, some nausea and vomiting. The fourth aspect is to rule out the possibility of encephalitis, it is recommended to go to the neurology department of the hospital for consultation.