Sleep directly influences how the nervous system manages stress, focus, and recovery. In this NightOwling lesson, circadian health expert and medical scientist Logan Pendergrast, Ph.D., explains how quality rest strengthens the parasympathetic branch of the nervous system, which promotes calm and restoration.
Dr. Pendergrast contrasts this with the sympathetic system, responsible for alertness and activation, showing how deep sleep helps maintain balance between the two. Research highlighted in this lesson shows that well-rested individuals experience up to a 30 percent reduction in cortisol, the body’s main stress hormone.
This segment explores how restorative sleep keeps the nervous system resilient and the mind clear under pressure.
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So speaking of parts of the body that
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are affected by sleep, we'll move into
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talking about the nervous system. So the
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nervous system is the part of our body
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that sends and receives signals and
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helps to coordinate our actions, our
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thoughts, and our sensations. And the
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nervous system breaks up into multiple
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parts, but one important part is the
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autonomic nervous system. Now the
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autonomic nervous system is basically
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just running in the background. It's the
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part of our nervous system that we're
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not really driving with our conscious
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thoughts. And that autonomic nervous
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system itself breaks up into two parts.
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One of those parts is the sympathetic
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nervous system. And that is the
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alertness part of our nervous system
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that makes us feel activated. And the
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flip side of the coin of that, if you
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will, is the parasympathetic nervous
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system. And that is the part of the
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nervous system that is responsible for
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making us feel relaxed. Now, the reason
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that I'm mentioning these parts of the
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nervous system is because after a night
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where we're experiencing deep sleep or
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effective sleep, we see a greater
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activation of the parasympathetic
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nervous system, meaning that we feel
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more relaxed and lower levels of stress.
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And this is actually shown in the
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research particularly by research that
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has been performed at Harvard where we
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see that individuals who sleep well have
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a 30% reduction in cortisol levels which
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cortisol is the primary hormone
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associated with feelings of stress.
