A person may feel groggy if they sleep too long during the day.
Sleep specialist, PhD Sofia Cherkasova explained why a person may feel groggy after a nap. According to the doctor, the reason for feeling unwell after daytime sleep is physiological processes that are triggered if a person sleeps too long. "If a person enters deep sleep during the day, serotonin begins to be produced too actively and can affect vascular tone. This leads to grogginess and headaches," she explained.
To avoid such negative consequences, Cherkasova recommended following a universal formula for safe daytime rest and sleeping for 15-20 minutes. This is enough to feel more alert, while during this time a person will not have time to enter deep sleep and will not experience the 'square head effect.' Additionally, according to her, one should wake up no later than 3 PM — this will help avoid problems with falling asleep at night.
If a person wakes up feeling groggy, Cherkasova advised taking a walk, doing some physical exercises, or drinking a cup of tea or coffee to normalize vascular tone.
