Can Your Eye Color Affect Your Risk of Seasonal Affective Disorder?

A study suggests that too much melatonin, more common in people with dark eyes, can contribute to seasonal depression.

For some people, colder temperatures and shorter days bring to mind beautiful winter wonderlands and cozy nights by the fire. Still, for others, winter can be downright depressing. 

Some people have seasonal affective disorder (SAD), while others don't. According to a study published in 2018 in the Open Access Journal of Behavioural Science & Psychology, your eye color may affect how prone to SAD you are.

A Study on Eye Color

Melatonin is a hormone that may affect SAD symptoms, like losing interest in hobbies, having less energy, and feeling depressed. The hypothalamus, a part of your brain, produces melatonin in response to light. So, as more blue and green light reaches your brain, the more melatonin the hypothalamus makes.

However, eyes with less pigment, like blue or gray eyes, are more sensitive to light than dark eyes. In other words, blue and gray eyes don't need to absorb as much light for cells to receive and process images as other eye colors.

So, according to the researchers, some people may have a high risk of SAD because of the amount of light that their eyes are able to process. In other words, having dark eye colors, which make more melatonin, may be a risk factor for SAD.

To investigate further, the study involved 175 undergraduate and graduate students from South Wales and Cyprus, with an average age of 24 years.

The researchers designed a questionnaire to screen for seasonal variability in the following:

  • Mood
  • Weight
  • Appetite
  • Sleep
  • Social activity

According to the researchers, students with light or blue eyes tended to score lower on the questionnaire than others, meaning those people didn't report much variability in factors like their mood, appetite, and sleep.

Also, the researchers found that people with light eyes released less melatonin during the fall and winter months.

Can Too Much Melatonin Make You Depressed?

Melatonin controls your sleep-wake cycle, helping you fall asleep at night and wake up in the morning. However, some evidence suggests that too much melatonin may make people feel lethargic or depressed.

Since your brain produces melatonin when it's dark, people have more melatonin in winter when the nights are longer than normal. In other words, less daylight may contribute to seasonal depression.

Therefore, light-eyed people who produce less melatonin may have some protection against SAD. According to the researchers of the 2018 study, blue eyes tend to occur in people living far away from the equator. The genetic mutation causing blue eyes may have occurred to protect people who live with short days year-round against SAD.

Tips for Seasonal Affective Disorder

Still, keep in mind that your eye color does not guarantee that you will or will not have wintertime depression symptoms. 

Likewise, eye color is not the only factor determining whether a person will develop SAD. For example, people who spend many hours indoors are also more vulnerable than others.

To treat SAD symptoms, try incorporating positive habits, such as:

  • Regularly exercising
  • Eating a healthy diet
  • Getting a good amount of sleep
  • Maintaining healthy social connections with other people

Light therapy may also help relieve SAD symptoms, regardless of a person's eye color. Light therapy involves exposure to a fluorescent light box with a diffusion screen for at least 30 minutes. If you don't have access to a light box device, spending time outdoors or sitting near a window during the daytime can help.

Still, one of the most effective treatments for seasonal depression is talk therapy and cognitive behavioral therapy (CBT). Some people with SAD may also benefit from antidepressants.

A Quick Review

Some evidence suggests that too much melatonin, which may be more common in people with dark eyes, can contribute to SAD. Fortunately, healthy habits, light therapy, psychotherapy, and antidepressants can help relieve SAD symptoms, regardless of your eye color.

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  1. Workman L, Akcay N, Reeves N, et al. Blue eyes keep away the winter blues: Is blue eye pigmentation an evolved feature to provide resilience to seasonal affective disorder?OA J Behavioural Sci Psych. 2018;1(1):1–7.

  2. National Library of Medicine. Seasonal affective disorder.

  3. Melrose S. Seasonal affective disorder: An overview of assessment and treatment approachesDepress Res Treat. 2015;2015:178564. doi:10.1155/2015/178564

  4. American Psychiatric Association. Seasonal affective disorder (SAD).

  5. Campbell PD, Miller AM, Woesner ME. Bright light therapy: Seasonal affective disorder and beyondEinstein J Biol Med. 2017;32:E13-E25.

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