Blue light and female hormones: Is this a thing?

Have you ever felt absolutely frazzled by the bright lights around you (especially the big light 🫣), while your partner seems completely unfazed? If you've found yourself irritated by screens and artificial lighting, there’s a reason for it—especially linked to blue light sensitivity!

Today's newsletter will give you the science behind this, and some free actionable tips you can implement starting now.

Recent research indicates that women might be more sensitive to this type of light than men, which can contribute to a range of health issues, including cortisol dysregulation and leptin resistance. Keep reading for the full article!

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A big trend with my clients & husbands/partners..

First I will start off by saying that this was a HUGE area of contention in my house for a long time ( it lasted until my husband actually saw a huge change in my health), and it is definitely a sticking point for many women who come to my community and 1:1 clients.

5 years fully into this lifestyle - my husband now understands the issues with blue light & keeps his phone screen on red - goes outside in the mornings with me & doesn't get mad (well not most of the time anyway 😂) when the house is fulled with red bulbs at night.

So today I want to show you some of the science around WHY women seem to have a visceral reaction to blue light - while the husband seems completely un-phased. Let's talk ⬇️

The optical system & vision differences between sexes:

• Visual Cortex and Testosterone: One reason is that men have about 25% more testosterone receptors in their visual cortex, the area of the brain that processes what we see. This gives men an edge when it comes to spotting differences in brightness and contrast—like recognizing faces or reading words on a page.
• Color Vision Superpowers: Women, on the other hand, have a knack for distinguishing colors, especially when it comes to shades of blue and green. This is thanks to the different types of color-detecting cells, called cones, in our eyes.
• Women have two types of cones on the X-chromosome: L-cones (which are sensitive to longer wavelengths of light, like reds) and S-cones (sensitive to shorter wavelengths, like blues). There’s also a third type called M-cones, which picks up middle wavelengths.
• Wavelength Perception: Here’s the interesting part—research shows that men typically need slightly longer wavelengths to see the same colors that women do. This means women are more adept at picking up those shorter wavelengths of blue light, which makes them more sensitive to its effects.

In summary - the differences in how our visual systems are constructed contributes to why women might feel more affected by blue light than men. (read more science on this)​

Melatonin Suppression:

​A study investigated the impact of evening light exposure on melatonin suppression in both men and women. The findings revealed that women experienced significantly greater melatonin suppression under bright light conditions (400 lux and 2000 lux) compared to men.

Specifically, at 400 lux, women showed a 93.7% ± 9.6% suppression, whereas men exhibited an 83.2% ± 18.7% suppression. At 2000 lux, the suppression was 99.5% ± 1.0% for women and 96.9% ± 4.3% for men.

These results suggest that women’s circadian systems are more sensitive to bright evening light, leading to greater melatonin supression.

Circadian Rhythms Matter

Have you noticed how tired you feel after scrolling through your phone late at night while your husband snoozes peacefully? Circadian rhythms, or our natural sleep-wake cycles, also differ between men and women by about 6 minutes.

Dr Renske Lok from Stanford University, who led the review, says: "While this difference may be small, it is significant. The misalignment between the central body clock and the sleep/wake cycle is approximately five times larger in women than in men.

Imagine if someone's watch was consistently running six minutes faster or slower. Over the course of days, weeks, and months, this difference can lead to a noticeable misalignment between the internal clock and external cues, such as light and darkness.

​Review the study here​

The Leptin & Metabolism Connection

The research team in this study looked into the possible link between rising obesity rates and insufficient sleep, noting that about 30% of adults aged 30 to 64 in the U.S. and Europe get less than six hours of sleep per night.

They found significant differences in how men and women's brains respond to food images after being sleep-deprived. Women exhibited twice the activation than men in brain networks related to decision-making and emotions.

Additionally, the study revealed that women had 1.5 times higher activation in the limbic region, which is involved in processing emotions, forming memories, and regulating behavior, when responding to images of sweet foods compared to men.

This suggests that sleep deprivation may impact women’s food-related decision-making and emotional responses more intensely than men's.

There is also ample evidence that women are much more likely to suffer from leptin resistance than men, but we will explore that in a future article!

What Does This All Mean?

In a nutshell, the sensitivity of women to blue light, combined with hormonal changes and distinct sleep patterns, can cause more stress and health issues (and a proclivity to leptin resistance), while men might not feel it as intensely.

As we continue to rely on screens & be surrounded by artificial lights, it’s important to take steps to protect ourselves.

Here are a few tips:

• Limit screen time before bed: Try to turn off devices at least an hour before sleep - wear blue blockers & keep lux below 10 the 3 hours leading up to bed (measure lux with MyCircadianApp)​
• Get morning sunlight daily before looking at screens. Consider wearing yellow blue blockers if you have to be up before the sun.
• Prioritize good sleep habits: Create a relaxing nighttime routine to help your body wind down & stop eating when the sun goes down or at least 3 hours before bedtime.

Need more help and support? Check out the 21 Day Leptin Reset Program!