The reasons why you may feel sleepy in spring are as follows:

• temperature difference
• stress
• disturbance of the autonomic nervous system
• Changes in daylight hours

First, we will explain each factor in detail.

temperature difference

The body maintains a balanced temperature regulation by consuming energy through such means as increasing blood volume and generating heat through muscles.
When there is a large temperature difference, more energy is used up, which leads to fatigue and drowsiness.
Spring is the season with the greatest temperature difference of the year. When the westerly winds pass around Japan, high and low pressure systems frequently alternate, causing pressure fluctuations and large daily temperature differences.

The difference between the maximum and minimum temperatures during the months of March to May, which are defined as spring, is as follows:

Month	(I.e.	(I.e.	Temperature difference
October	17.9 ℃	8.6 ℃	9.3 ℃
October	21.7 ℃	11.9 ℃	9.8 ℃
October	24.0 ℃	14.6 ℃	9.4 ℃

(reference:Japan Meteorological Agency | Various data and materials Monthly values ​​(2023)

Between March and May, there is an average temperature difference of 3 degrees Celsius, and in fact, about 5% of people feel the temperature difference.^{※ 1}

stress

Spring is a time when there are many changes in living environment and relationships, making it easy to feel stressed.
When we feel stressed, our brains escape from reality and enter a state called "dissociation."
Dissociation is one of the mind's defense instincts, and symptoms include drowsiness, fatigue, emotional numbness, amnesia, and flashbacks.

In addition, stress often reduces hormone secretion, resulting in poor quality sleep and making you feel sleepy during the day.

Melatonin plays a major role in the quality of sleep.
Melatonin is a "sleep hormone" that relaxes the mind and helps you fall asleep smoothly. Its secretion is normally suppressed during the day and increases at night.
However, if you live a stressful life, your body may lack melatonin, making it difficult to fall asleep, which can result in excessive daytime sleepiness.

disturbance of the autonomic nervous system

The autonomic nervous system is a peripheral nerve that is distributed throughout the body, including the hypothalamus and spinal cord in the brain. There are two types of nerves: sympathetic and parasympathetic, and their characteristics and roles are as follows:

Types	Features	role
Sympathetic nerve	Become active during the day Responds to tension and stress	Increases heart rate and blood pressure Increase energy expenditure
Parasympathetic nervous system	Work in the evening and at night Works even while you sleep	relax mind and body Promotes sleep

The sympathetic and parasympathetic nervous systems support vital functions by maintaining a balance with each other, but it is said that this balance is easily disrupted during seasonal changes.
When the sympathetic nervous system, which is normally only active during the day, becomes dominant at night, the brain becomes alert and unable to sleep, which can lead to chronic drowsiness.

Changes in daylight hours

The amount of sunlight also affects melatonin.
When the daylight hours get longer in the spring, the secretion of melatonin tends to be suppressed, but because the changes in daylight hours are so sudden in the spring, it can be difficult for the body to adjust until the melatonin secretion rhythm stabilizes.
As a result, you may experience symptoms such as "having trouble waking up refreshed in the morning," "not feeling sleepy at night," or "feeling sleepy during the day."

Sleep problems may be caused by the following:

• Psychological factors such as stress and anxiety
• Physiological factors, including disruptions to the body clock
• Factors such as living environment and habits

In the next chapter, we will introduce methods that can help resolve sleep problems, as well as suspected illnesses.

Record your sleep

By looking back at your own sleep state, you can understand the length and regularity of your sleep, which can help resolve sleep problems.

There are the following types of methods for recording your sleep:

• Sleep diary
• Sleep Tracker
• Sleep Monitor
• sleep app
• Wearable device

The items will vary depending on the recording method, but they mainly include the time you went to bed, fell asleep, and woke up, the time you woke up in the middle of the night, your mood when you woke up, how much sleepiness you felt during the day, and the time of day when you took a nap or dozed off.

It is important to keep recording your sleep for about 1 to 2 weeks.

There may be a sleep disorder

If drowsiness interferes with your daily or social life, a sleep disorder may be suspected.

The main types of sleep disorders are:

• insomnia
• Hypersomnia
• Obstructive sleep apnea syndrome
• Parasomnia
• Restless Legs Syndrome

Insomnia is a condition in which you have difficulty falling asleep, wake up many times during the night, or wake up early in the morning and cannot fall asleep, leading to strong daytime sleepiness and fatigue, as well as a decrease in motivation, concentration, and appetite. 30-40% of Japanese people suffer from insomnia, and it is particularly prevalent in women.^{※ 2}

With hypersomnia, even if you get enough sleep at night, you may feel very sleepy during the day and have difficulty waking up.

Obstructive sleep apnea syndrome is a respiratory disease caused by enlarged tonsils, allergies, obesity, etc. Breathing stops during sleep, causing a lack of oxygen in the body, which causes strong sleepiness during the day.

Other sleep disorders include parasomnias, which include sleepiness, bedwetting, and teeth grinding while sleeping, and restless legs syndrome, which causes unpleasant numbness inside the legs.

Finally, we will introduce some easy ways to deal with sleepiness this spring. If you want to get rid of sleepiness, please refer to them.

Incorporate it into your lifestyle and live a vibrant life every day.

Take a shower after waking up

When you take a shower after waking up, the water flow and heat activate your sympathetic nervous system, raising your blood pressure and clearing your head.
In addition, improved blood circulation can also help relieve fatigue.

Showers do not need to be long; 5 to 10 minutes is enough. Also, soaking in a bathtub relaxes both the body and mind, so it is best to avoid taking a shower when you wake up.

Basking in the morning sun

The morning sun promotes the secretion of cortisol and serotonin, which have an awakening effect in the brain, and resets the body clock.
Your body will switch to active mode and eliminate sleepiness, allowing you to be active throughout the day. When it comes to getting morning sunlight, it is more effective to do it outdoors than indoors. Be careful not to look directly at the sun, and try to sunbathe for about 1 to 1 minutes a day.

Be careful not to expose yourself to the sun for long periods of time, as this can cause skin problems such as blemishes and freckles.

Take a nap

Taking a nap can help reduce drowsiness and improve your performance.
Taking a long nap will cause you to fall into a deep sleep, which will negatively affect your nighttime sleep, so naps of around 15 to 20 minutes are recommended.
The best time to take a nap is between 12 noon and 15 pm, when you are most likely to feel sleepy.

Also, to help you wake up more easily, it's important not to lie down completely, but to sit in a chair or lean back in a recliner.

It is said that drinking a caffeinated drink such as coffee, black tea, or green tea before taking a nap will help you wake up more refreshed.

Use the scent

If you feel sleepy, try using fragrant aromas.

• Lemon
• orange sweet
• Grapefruit
• peppermint
• Mint

Citrus aromas such as lemon, sweet orange, and grapefruit contain a compound called limonene. Limonene has the effect of stimulating the sympathetic nervous system, and is expected to have the effect of waking you up and clearing your head.

Additionally, herbal aromas such as peppermint and menthol, which have a refreshing feel, are also recommended when you want to activate your brain.

Improve your sleep quality with lactic acid bacteria

The most effective way to combat sleepiness is to improve the quality of your sleep.

Lactic acid bacteria have the effect of improving the intestinal environment, which is necessary for improving sleep quality.
Gut bacteria are involved in the production of melatonin, the sleep hormone, and short-chain fatty acids necessary for resetting the body's internal clock (circadian rhythm).

In addition, the gut and the brain have a mutually influential relationship, so improving your intestinal environment may also help reduce stress.

Foods that are rich in lactic acid bacteria include:

• Dairy products such as yogurt and cheese
• Fermented foods such as natto and miso
• Supplements containing lactic acid bacteria

If you take a large amount of lactic acid bacteria all at once, it will be excreted from the body, so it is important to continue taking it every day.

In this article, we will focus on the causes and solutions to spring drowsiness.

In many cases, the strong feeling of sleepiness that occurs in spring is related to temperature changes, stress, and autonomic nervous system disorders.
It may also be that your sleep quality is declining.

Improving your living environment and habits and taking lactic acid bacteria can effectively improve the quality of your sleep.

Let's refresh our mind and body and enjoy spring to the fullest.