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The Skin–Brain Connection: How Sunlight Influences Serotonin, Mood and Psychiatric Disorders - Wisdom wednesdays · Hardiness with Dr Paul Taylor

• 0:05
  Speaker 1: Hey, everybody, welcome to another edition of Wisdom Wednesdays.
• 0:09
  Speaker 2: Today we're going to talk about something that's pretty.
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  Speaker 1: Simple but has a big impact on our biology, and
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  Speaker 1: that is sunshine. I've just read a pretty interesting paper
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  Speaker 1: that's been published in the Innovations in Clinical Neuroscience. The
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  Speaker 1: title of the paper Sunshine, Serotonin and Skin A Partial
• 0:27
  Speaker 1: Explanation for Seasonal Patterns in Psychopathology. It's a bit of
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  Speaker 1: a mouthful, but basically it explores something I think we
• 0:36
  Speaker 1: massively underestimate in modern health conversations, and that is the
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  Speaker 1: relationship between light exposure, serotonin, mood disorders, and even suicide.
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  Speaker 1: Now we've known for a long time that psychiatric symptoms
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  Speaker 1: can follow seasonal patterns, and it's even mentioned in the
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  Speaker 1: DSM five. It includes a with seasonal pattern specifier for
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  Speaker 1: depressive disorders because we see that mood disorders, anxiety disorders,
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  Speaker 1: and even completed suicide they show fluctuations across the year.
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  Speaker 2: Now here's where it gets interesting.
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  Speaker 1: We've always assumed that the mechanism was primarily through the eyes,
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  Speaker 1: where a light hits the sun from the sun hits
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  Speaker 1: the retina and that signal and then travels to something
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  Speaker 1: called the raffi nuclei and then your serotonin shifts and
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  Speaker 1: your mood changes, and it's pretty neat, it makes sense.
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  Speaker 1: But this paper proposes something a bit more intriguing, and
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  Speaker 1: that is that your skin might be directly involved. And
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  Speaker 1: it turns out that these seasonal mood changes might not
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  Speaker 1: just be winter blues. There are a number of large
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  Speaker 1: research studies that shows that there's worsening depressive symptoms in
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  Speaker 1: the winter months, and everybody gets that, particularly if you
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  Speaker 1: live somewhere where it gets dark a lot where I'm from.
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  Speaker 1: But we know that there's increased anxiety, there's also seasonal
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  Speaker 1: shifting bipolar disorder, and we also know that serotonin levels
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  Speaker 1: in healthy individuals also fluctiate seasonally, their lowest in winter
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  Speaker 1: and their highest and late summer in autumn, and that
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  Speaker 1: has a big impact on our mood. So clearly there
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  Speaker 1: is a biological signal that is responding to light availability,
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  Speaker 1: and this research paper is saying that it's not just
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  Speaker 1: the eyes that are involved, but also the skin.
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  Speaker 2: So the researchers high added.
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  Speaker 1: That human skin contains the machinery necessary to produce serotonin,
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  Speaker 1: and this is a bit of a game changer. So
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  Speaker 1: something called tripped upon hydroxyle is. This is the the
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  Speaker 1: real limiting enzyme for serotonin synthesis. What that means, a
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  Speaker 1: real limiting enzyme is something that if it's not there,
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  Speaker 1: if the enzyme is not there, it actually impacts upon
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  Speaker 1: this pathway. Right, So this trip to pane hydroxylea is
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  Speaker 1: actually present in our skin. So serotonin itself is finding
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  Speaker 1: in what are called keratinocytes, and serotonin transporters are present
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  Speaker 1: there too, So this is in the skin.
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  Speaker 2: So it turns out your skin isn't just a passive barrier.
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  Speaker 1: It's actually active neurochemically. And there's actually an evolutionary argument
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  Speaker 1: for this that they discussed in the paper.
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  Speaker 2: The brain and the skin.
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  Speaker 1: The epidermis, that's a layer of the skin sure a
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  Speaker 1: common embryological organ, and that's called the ectoderm. So there
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  Speaker 1: are three germ layers that we develop from the ectoderm,
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  Speaker 1: the endoderm, and the mesoderm.
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  Speaker 2: So it turns out that our brain and our skin.
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  Speaker 1: Are actually related biologically at that very very initial level.
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  Speaker 1: And some researchers suggest that the skin setgic system or
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  Speaker 1: serotinergic sorry system may be an evolutionary remnant of an
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  Speaker 1: ancient ancestral peripheral serotonin system. It was just a bit
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  Speaker 1: of a mouthful to say that. Basically, the skin has
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  Speaker 1: been involved for millions of years.
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  Speaker 2: So what they did is one experiment.
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  Speaker 1: The participants were exposed to light while worrying opaque goggles
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  Speaker 1: to block retinal input, and even with the eyes basically
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  Speaker 1: shut down to the light, those who were exposed to
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  Speaker 1: light had higher serum serotonin levels and it was through
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  Speaker 1: the skin pathway, and that means that sunlight can directly
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  Speaker 1: stimulate serotonin production via the skin, and that's probably why
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  Speaker 1: we all feel a shitload better in the summer, and
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  Speaker 1: we instinctively seek the sun in winter, and it may
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  Speaker 1: be that it's just our basic neurobiology that's driving that desire.
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  Speaker 2: So let's just make the pathway really really simple.
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  Speaker 1: Sunlight hits the skin and then cutaneous or skin serotonin
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  Speaker 1: production increases, and then you get systemic shifts in your
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  Speaker 1: serotonin levels, and then your mood regulation and improves. So
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  Speaker 1: serotonin isn't just about happiness. It actually regulates mood stability.
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  Speaker 1: It has an impact on anxiety, It has an impact
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  Speaker 1: on sleep, on appetite, on impulse control, and all of
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  Speaker 1: these things are highly highly relevant to psychiatric disorder, so
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  Speaker 1: impulse control is heavily implicated in ADHD as well. So
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  Speaker 1: this gives us a partial biological explanation for this sad
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  Speaker 1: thing that we see seasonal effective disorder and also seasonal
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  Speaker 1: worsening of depression. Less sunlight equals less photo stimulation, and
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  Speaker 1: that means lower serotonin. Now let's layer this over circarean biology.
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  Speaker 1: So light is the primary regulator of your super chismatic nucleus,
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  Speaker 1: that's the master clock.
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  Speaker 2: It sits right.
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  Speaker 1: Behind your forehead, and morning light suppresses melatonin and it
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  Speaker 1: elevates cortisol. Appropriately, we need cortisol to give us energy
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  Speaker 1: to attack the day. Daytime light increases alertness and stabilizes mood,
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  Speaker 1: and then that evening darkness allows melatonin to rise. So
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  Speaker 1: if we disrupt that pattern with dim days and bright
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  Speaker 1: nights the lights at night, we dese stabilize our Circian rhythms.
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  Speaker 1: And I've talked on this podcast many times before about
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  Speaker 1: what happens when you mess with circarean biology. Basically, you
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  Speaker 1: significantly increase depression by polar disorder, anxiety, and psychosis, as
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  Speaker 1: well as a whole heap of physical issues which we
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  Speaker 1: won't even talk about in this podcast. So light isn't
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  Speaker 1: just mood decoration, it's a metabolic and psychiatric infrastructure.
• 6:53
  Speaker 2: And then we need to talk about vinamin date.
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  Speaker 1: I have dedicated almost an entire chapter in my new
• 7:00
  Speaker 1: book the hardiness effect of vitamin D because it's hugely important.
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  Speaker 1: It shouldn't actually be called a vitamin. It's actually a
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  Speaker 1: steroid hormone. And when UVB rays from the sun hit
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  Speaker 1: your skin, they convert seven at D hydro cholesterol into
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  Speaker 1: vitamin D three, which is then activated in your liver
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  Speaker 1: and your kidneys.
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  Speaker 2: And that active form that comes out.
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  Speaker 1: Of your living in your kidneys is called calcatrol that
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  Speaker 1: binds the vitamin D receptors in nearly every tissue in
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  Speaker 1: your body.
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  Speaker 2: This is why vitamin D is so important.
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  Speaker 1: It regulates hundreds and hundreds and likely thousands of genes.
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  Speaker 2: Research is now discovery.
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  Speaker 1: We now know that vitamin D influences DNA repair, it
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  Speaker 1: suppresses inflammation, It has a positive role on the function
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  Speaker 1: of your mitochondria, It modulates your immune system. It actually
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  Speaker 1: plays a role in neurotransmitter synthesis, telemere stability, and in autopogy.
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  Speaker 1: That's kind of cleansing, cellular cleansing, and basically these vinamin
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  Speaker 1: D receptors that are also present in Brian regions involved
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  Speaker 1: in mood and cognition. And we see that lower vitamin
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  Speaker 1: D is associated with high rates of depression, and actually
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  Speaker 1: interventions using vinamin D for depression are actually pretty successful.
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  Speaker 2: So here's there's another pathway.
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  Speaker 1: Sunlight activates UVB or our releases UVB that triggers vitamin
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  Speaker 1: D synthesis, that regulates our genes and a whole heap
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  Speaker 1: of other shit, and that lends us leads us to
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  Speaker 1: a positive mood, lower inflammation, and neuroprotection as well. Now
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  Speaker 1: remember this sunscreen blocks about ninety five percent of vitamin
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  Speaker 1: D production, and that leads us to this modern problem.
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  Speaker 1: And I've read about this in my book I come
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  Speaker 1: from Northern Ireland with the sun was a mythical creature.
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  Speaker 1: Anytime it was out, everybody was out with their tops off.
• 9:00
  Speaker 1: And then it came to Australia and it was like
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  Speaker 1: this was something that was evil and to be avoided.
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  Speaker 1: And that's because obviously of skin cancer. And you know,
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  Speaker 1: it is right that we can't have too much because
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  Speaker 1: we increase our risk of skin cancer. But the researcher
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  Speaker 1: is now showing low vinamin D increases the risk of
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  Speaker 1: many other cancers. So by avoiding excessive UV, we may
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  Speaker 1: have drifted into chronic light deficiency and that is associated
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  Speaker 1: with lower serotonin, disturbed circadian rhythms, lower vitamin D, increased depression,
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  Speaker 1: increased anxiety, and potential seasonal exacerbation of a whole host
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  Speaker 1: of psychiatric illnesses. So the solution isn't to go out
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  Speaker 1: there and just recklessly expose yourself to the sun. It's
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  Speaker 1: about intelligent exposure. It's about getting enough but not getting
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  Speaker 1: too much.
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  Speaker 2: It's really the Goldilocks effect.
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  Speaker 1: So it's really to b see if it's get regular
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  Speaker 1: morning light exposure when the sun isn't who's strong, aim
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  Speaker 1: for short, sensible mid day sun exposure based on your
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  Speaker 1: skin type. You can actually look that up. I think
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  Speaker 1: it's called the Fitzpatrick skiel. And obviously if you're peel
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  Speaker 1: you need less time in the sun than if you've
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  Speaker 1: got dark skin. But for me, the big thing, get
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  Speaker 1: your vimin le D levels tested. Don't guess, get them tested.
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  Speaker 1: Go to Omega quant O M E G A q
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  Speaker 1: U A N T and for about sixty Australian dollars
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  Speaker 1: you can get it tested. I got no association with
• 10:30
  Speaker 1: these guys. I just love that they will test your
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  Speaker 1: vinmin D levels. They'll also test your Omega three fatty acids,
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  Speaker 1: which you should do while you're at it. So that
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  Speaker 1: is pretty much that for this week, folks. We need
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  Speaker 1: to get enough sun exposure and overall light exposure and
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  Speaker 1: your brain and your mood will thank you for it.
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  Speaker 2: That's it for this week, folks. Catch you next time.