Taking a nap is recommended to spend afternoon actively, but incorrect nap raises the risk of cerebral infarction. In the case of elderly people, taking a nap for more than 1 hour increases the risk of cerebral and cardiac infarction.
When you go into deep sleep, waking up from it increases burden on the blood vessels and raises the blood pressure, increasing the risk of cerebral and cardiac infarction.
When you sleep, the blood vessels expand, but when you wake up, the blood vessels contract suddenly, giving a heavy burden to the blood vessels.
It is good to drink a cup of hot coffee before taking a nap because caffeine in coffee will take effect in 20 to 30 minutes so you can wake up feeling well. Ideal duration of nap is 15 minutes.
15 minutes nap also prevent dementia. Amyloid β (beta) is known as a cause of dementia, which attacks and decreases neurons in the brain, but amyloid β melts and is discharged while you are sleeping. However, sleeping more than 60 minutes increases the risk of dementia because it causes sleep at night to be shallow, shorten the time to clean amyloid beta.