How bright light exposure affects cortisol levels | Satchin Panda
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Cortisol, a steroid hormone that participates in the body’s stress response, is produced in humans by the adrenal gland. Several factors influence its release, including stress. Exposure to bright light also promotes the release of cortisol, and, in turn, the hormone drives wakefulness during the daytime hours. Chronic stress and mis-timed exposure to light can dysregulate cortisol release and promote aging, however. In this clip, Dr. Rhonda Patrick describes how bright light exposure drives cortisol release.
Rhonda: I remember reading some study that was published some years ago where humans that were exposed to around, I think it was around 10,000 lux of light, upon, you know, 30 minutes of waking, so, um...
Satchin: Yeah.
Rhonda: ...you know, early exposure, and they were exposed to it for a number of hours, something like seven hours. I mean, it was, like, bright light, you know, all day, almost like being outside.
Satchin: Yeah, yeah.
Rhonda: And then their cortisol levels were measured at various points in the day. And so cortisol is one of those hormones that's regulated by this, the circadian clock.
Satchin: Yeah.
Rhonda: And it peaks about the time we wake up...
Satchin: Yeah.
Rhonda: ...or something like that, right?
Satchin: It rises when we wake up. So that promotes alertness, and melatonin is the opposite, it [laughs] promotes sleep.
Rhonda: Right. And it also...I mean, cortisol regulates... in itself, it's regulating...
Satchin: Yeah, huge amount.
Rhonda: …you know, 20% of protein-coding genes.
Satchin: Yeah.
Rhonda: So it's doing a lot. But these people...the thing with cortisol you want it to peak when it's supposed to peak.
Satchin: Yeah.
Rhonda: And you don't want it to be active all the time. You know, things like chronic stress...
Satchin: Yeah.
Rhonda: ...that can activate cortisol and, you know, this can lead to dysregulation of, you know, 20% of the human genome...
Satchin: Yeah.
Rhonda: ...or something like that. Anyways, these people that were exposed to the bright light had a 20% or 25% decrease in cortisol levels, you know, during parts of the day when it wasn't supposed to be high.
Satchin: Yeah.
Rhonda: It's very interesting how just the bright light exposure itself...
Satchin: Yeah.
Rhonda: ...seem to regulate the stress hormone or at least keep it…
Satchin: Yeah.
Rhonda: …so it wasn't going out of control.
Emotional pressure suffered for a prolonged period over which an individual perceives he or she has no control. It involves an endocrine system response in which occurs a release of corticosteroids.
A steroid hormone that participates in the body’s stress response. Cortisol is a glucocorticoid hormone produced in humans by the adrenal gland. It is released in response to stress and low blood glucose. Chronic elevated cortisol is associated with accelerated aging. It may damage the hippocampus and impair hippocampus-dependent learning and memory in humans.
A hormone that regulates the sleep-wake cycle in mammals. Melatonin is produced in the pineal gland of the brain and is involved in the expression of more than 500 genes. The greatest influence on melatonin secretion is light: Generally, melatonin levels are low during the day and high during the night. Interestingly, melatonin levels are elevated in blind people, potentially contributing to their decreased cancer risk.[1]
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