Feeling unusually tired, irritable, or unmotivated this October? The problem might not be your workload. A study involving 103 adults identified different sleep and circadian rhythm patterns associated with seasonal depression. Now, an October 23 warning from the University of Alabama at Birmingham explains why shorter fall days can affect mental health before winter arrives.
Stephen Thomas, PhD, associate professor of psychiatry and behavioral neurobiology at the University of Alabama at Birmingham, says seasonal affective disorder (SAD) doesn’t always begin with sadness. Changes in energy, sleep, appetite, and motivation can be warning signs. With daylight saving time ending November 1, the timing matters, although the clock change itself isn’t the primary cause.
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Why Shorter Days Can Change Your Mood
Less sunlight can disrupt biological systems governing sleep and emotional regulation. According to the National Institute of Mental Health, seasonal depression is associated with changes in circadian rhythms and chemicals involved in mood.
“Some people will also describe being more irritable than sad,” Thomas said.
Geography matters, too. Thomas notes that Bangor, Maine, receives approximately 15.5 hours of daylight around the summer solstice, compared with 8.75 hours in winter.
“We are able to identify both biological and behavioral explanations for SAD,” Thomas said. “Light is so important for many things, including sleep, mood and cognition.”
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The Warning Signs Aren’t Always Obvious
Seasonal depression can affect everyday routines, including exercise, concentration, and social activities. Persistent changes deserve attention rather than being dismissed as ordinary fall fatigue.
Thomas says symptoms vary considerably. Some people experience disrupted sleep or appetite, while others lose interest in activities they previously enjoyed.
Physical activity may help. Exercise supports mental health, although it isn’t a replacement for professional treatment.
Not everyone experiencing lower energy has seasonal depression. SAD involves a recurring seasonal pattern, and other medical or psychological conditions can produce similar symptoms.
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What Experts Recommend Before Winter
Thomas recommends increasing daylight exposure and maintaining physical activity. The American Psychiatric Association also identifies consistent sleep, exercise, and social connection as useful strategies.
For diagnosed winter-pattern SAD, clinicians may recommend morning bright-light therapy, psychotherapy, or medication. Light boxes require appropriate precautions, particularly for people with certain eye conditions or bipolar disorder.
For those getting less sunlight during fall and winter, Clearlight’s SUN ONE UVB Wellness Lamp is designed to support natural vitamin D production, although it isn’t an established treatment for seasonal depression.
“If the symptoms negatively impact their life in any way, it is probably worth speaking with someone about their symptoms,” Thomas said.
The takeaway: Protect your sleep schedule, get outside during daylight, and keep moving. If mood changes persist or interfere with daily life, seek professional evaluation rather than waiting for spring.
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