Reference; https://mbp-japan.com/jijico/articles/32380/
Modified and translated by CFJA
Table of Contents
Late-Night Eating Can Lead to Sleep Deprivation
Sleep is regulated by areas of the brain such as the hypothalamus and brainstem. The anterior hypothalamus contains the sleep center, while the wakefulness center spans from the posterior hypothalamus into the brainstem. These two centers work together to maintain a balance between sleep and wake states.
A key neurotransmitter involved in this process is orexin, which is also used as a target in certain sleep medications. During sleep, the release of orexin is significantly reduced. While scientific understanding of sleep mechanisms has gradually progressed, much remains unknown.
Among the various causes of sleep disorders, one factor commonly seen in modern life is late-night eating, which can contribute significantly to sleep deprivation.
In particular, eating after 10:00 PM can stimulate digestive activity during the body’s naturally sleepiest period, around 11:00 PM. Since sleep occurs in 90-minute cycles (alternating between feeling sleepy and not sleepy), the next drowsy phase may not occur until around 12:30 AM.
If one takes a bath after eating, body temperature will temporarily rise, and it typically takes about two hours after this increase for the body to feel sleepy again. This means drowsiness might not return until around 2:00 AM, about 90 minutes later.
As a result, sleep quality declines, the internal organs remain fatigued, and one wakes up without proper recovery.
For example, if someone wakes up at 7:00 AM, their total sleep time may only be 5 to 6.5 hours, far less than the recommended amount.
Chronic sleep deprivation leads to reduced cognitive function. If such a lifestyle continues for more than 10 years, it can trigger brain atrophy and potentially place one in the early stages of Mild Cognitive Impairment (MCI).
Eating Too Quickly Leads to Slower Digestion and Internal Fatigue
The Japanese are often known for their strong work ethic—even to the point of sacrificing mealtime for work. One common example of this is eating too quickly. People who eat quickly tend to swallow food without chewing it properly.
In traditional Japanese education, it was taught that during meals, “After placing a bite of rice into your mouth, put your chopsticks and hands on your lap, chew at least 30 times, and only then swallow.” Particularly with brown rice, this level of chewing is essential, and meals can take over 30 minutes as a result.
Chewing thoroughly stimulates the production of saliva, which in turn triggers the release of digestive juices such as gastric acid. This chain reaction is ideal for smooth and effective digestion.
Research has shown that someone who eats for 30 minutes straight has more sustained energy than someone who eats for 5 minutes and then rests for 25 minutes.
When you eat quickly, this natural digestive cascade doesn’t occur properly. As a result, the digestive organs are overworked, and digestion takes longer, leading to internal fatigue.
Additionally, eating too quickly often leads to overeating, as one can consume a large amount of food before the sensation of fullness kicks in.
If a person eats a large meal after 10:00 PM, this can intensify the burden on the digestive organs. The result is sleep deprivation and a more rapid decline in cognitive function.
For those who eat quickly and late at night, it is essential to eat smaller portions and chew slowly in order to prevent the onset of Mild Cognitive Impairment (MCI).
As people age, the number of teeth decreases, making proper chewing more difficult. Therefore, maintaining good oral health becomes especially important.