#1

From Siimland on X

“Aging flattens your circadian hormones, which worsens sleep-wakefulness cycles and disrupts other hormones”

Big amplitude in cortisol, melatonin, and body temperature is characteristic of youth.

Need medicine to sleep and caffeine to wake…sound familiar?

It’s always the cycles that matter. How to recover the amplitudes (peaks and valleys)?

https://www.nature.com/articles/s41583-018-0088-y

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#2

I wish the paper had a handy graphic overview for “Later life” like they do for adolescents…

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That said, seems like the same “Interventions” would help (at least a bit).

As you suggest, we can control supplementing with melatonin.

Additionally, I’ve seen a number of studies identifying the variation of light intensity (e.g., bright sunlight early in the morning vs the darkness in the evening) as driving melatonin levels.

I experienced this most dramatically during and following hurricane Sandy. We lost power for a several days here in lower Manhattan. The darkness and quiet of the city provided a profoundly different environment than normal life. Once the sun set we lived by candle light. I don’t remember ever sleeping better, sleeping more deeply, or feeling so rested.

The quiet, and fall in temperature during the power outage might have also contributed to sleep quality.
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Some twenty years ago the NY Times Magazine had an article on an experiment where a family lived for a year in a remote location (away from city lights and noise) without electricity. Their daily rhythms quickly converged to them rising with the sun and going to sleep at sunset.

They reported profound changes in alertness and productivity as well as a broader and expansive experience of sleep and dreaming.

I don’t think anyone measured their body temperature, cortisol, and melatonin levels.
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The paper only mentions cortisol a couple of times in its text.

The flattening of cortisol during sleep surprises me. I don’t remember seeing this reported in the past.

Cortisol rhythms peak earlier in the morning during childhood and, with age, gradually widen and reduce in overall amplitude. The amplitude of rhythmic gene expression in the brain and other tissues is reduced during ageing, affecting tissue homeostasis and function (not shown).

Things like HIT and HIIT could increase cortisol during the day, but would this alter the flattened curve?
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re: caffeine

Cortisol fluctuates with increases and decreases in negative affect

Caffeine also increases cortisol and epinephrine levels both at rest and during periods of stress (al’Absi and Lovallo, 2004).

…but I don’t think this would raise cortisol during sleep.

I wonder if cortisol rises in response to REM sleep and dreaming?

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#3

I experienced this exact thing with my wife, when we used to do a lot of camping some 15-20 years ago. We would go to sleep when it got dark, and get up when it was dawn. We camped in remote areas, not campgrounds. Lots of crazy stories with nature so up close, coyotes and bears walking right past the tent :slight_smile: . But yes, extremely restful, natural feeling sleep, and getting up full of energy… effect so powerful, I’d swear to keep it up when we got back home, but as usual, life gets in the way, artificial light, deadlines, reading, watching, and back to disordered skeep, waking up at night, mornings hard to get up and so on. Camping was always a big reset. Miss those days.

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#4

I recently interviewed a light expert who said blue/ “white” LED light raises cortisol. The red end of the spectrum including NIR raises melatonin. When you get both (sunlight or other full spectrum) the melatonin turns down the cortisol. With only the blue light you just get the higher cortisol. Don’t throw out your incandescent bulbs.

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#5

Pretty sure they stopped making them. In fact I think it may be illegal to make them.

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#6

@Bicep

This is where I’m buying my incandescent bulbs. Use an old fashioned dimmer … turn them way down to make them last a long time. You don’t need the visible light…just the NIR. Let it bounce around until it finds you.

Also, crack (a few inches) your windows when driving the car to let the NIR light get in.

#7

How do you handle the twice yearly time change? Personally, I find it very annoying, I’d much prefer if they’d just pick one and stuck to it. I always feel my body thrown for a loop with this yanking around. Do you keep to the old schedule of sleep/wake (so now you sleep/wake one hour different from the official clock), or do you actually change your routine of wake/sleep to accomodate the new time? I kind of think about it as about the time pieces around the house - I change the time on my main clocks around to match my computer/phone, but leave the old time on random clocks in like appliances, so my coffee maker will be off by an hour part of the year. What do you do with your body, keep it steady time, like the coffee maker, or keep changing to sync with your phone? I keep my body on coffee maker time :grin:.