"Does 'Summer Fatigue' Set In in September?"

“September Sickness”: When Summer Fatigue Sets In

“Does Summer Fatigue Hit in September?” — What Is It, Really?

“I thought I’d made it through the summer, but as soon as September rolls around, I suddenly feel sluggish.”
Low mood, difficulty getting up, and lingering fatigue can become noticeable around the change of season.

Actually, this might be a phenomenon known as “September Sickness”.
This guide explains the true nature, symptoms, causes, and countermeasures for September Sickness, incorporating the latest information.

What Is September Sickness? How It Differs from Summer and Fall Fatigue

First, let’s clarify the context of the term “September Sickness.”

Summer Fatigue
Mainly characterized by loss of appetite and fatigue caused by the high temperatures and humidity of midsummer.
Fall Fatigue
A sense of lethargy that persists from September through October. Primarily caused by temperature fluctuations and the effects of air conditioning.
September Syndrome
Physical and mental lethargy and low mood that appear once temperatures stabilize in September.
Medically, it is a concept similar to “seasonal autonomic imbalance” or “mild seasonal depression.”

👉 The key point is that “the fatigue accumulated over the summer surfaces in September.”

Main Symptoms of September Blues

The symptoms of September Blues vary widely, but the most common ones are as follows:

Difficulty waking up in the morning, shallow sleep
Loss of appetite or overeating
Low mood, lack of motivation
Stiff shoulders, headaches, dizziness
Severe fatigue, difficulty concentrating

A survey by the Ministry of Health, Labor and Welfare also reports that the number of people complaining of physical discomfort during seasonal transitions is increasing year by year, with a particularly high percentage of people in their 20s through 40s reporting “lethargy and low mood” (2024 survey).

Why Do People Feel Unwell in September?

“September Sickness” is caused by a combination of several factors.

1. Disruption of the Autonomic Nervous System Due to Temperature Fluctuations

“Temperature fluctuation stress” caused by hot days and cool mornings and evenings
The strain of regulating body temperature disrupts the autonomic nervous system

2. Aftereffects of Summer Fatigue

Strong UV rays, lack of sleep, and air-conditioning fatigue
Accumulated fatigue surfaces at the start of fall

3. Decrease in Daylight Hours

Daylight hours shorten rapidly in September
Serotonin secretion decreases, leading to low mood (mild seasonal depression)

4. Stress from the New School Year and Work

School and workplace routines resume
Mental stress directly affects physical health

Ways to Prevent and Alleviate “September Blues”

1. Establish a Regular Daily Routine

Stick to a consistent bedtime and wake-up time
Avoid using your smartphone before bed to promote deep sleep

2. Focus on a Balanced Diet

Incorporate fall foods (Pacific saury, mushrooms, sweet potatoes)
B vitamins, iron, and omega-3 fatty acids are particularly effective

3. Make Light Exercise a Habit

Morning stretching or walking
Exposure to sunlight stimulates serotonin production

4. Mental Health Care

Understand that “feeling sluggish isn’t your fault”
If you experience persistent low mood, consult a specialist as soon as possible

In Closing—Understanding “September Blues” for a Healthy Fall

“September Blues” isn’t just “laziness” or “all in your head”—it’s a sign that your body and mind are out of sync.
Simply having the right knowledge can reduce anxiety and make it easier to take action.

Fall is the season for enjoying good food and outdoor activities.
With a few simple adjustments, you should be able to enjoy this fall with more energy.

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