From a newsletter I receive:

Note that it's not just the number of hours of sleep that is important to health, but the darkness as well.

You can go to the Journal of the National Cancer Institute

https://jncicancerspectrum.oxfordjournals.org/

and get 25 results if you search for "melatonin."

It's free to download PDF copies of articles if they're more than a year old. :wink:

Gerry

From the quoted text: It does? The body has a teeny tiny little clock that tells melatonin when it's 1:30 a.m.?

It's just difficult to believe that the body, when sleeping in complete darkness, knows if it's 1:30 a.m. or 1:30 p.m.

Sounds suspicious to me. :wink:

Yes, it does.

Not necessarily for the actual clock time, but for the darkness time. And this "teeny tiny little clock" goes haywire if we veer away from actual darkness time.

And not only for melatonin (it's also the first time I heard of 1:30 am), but also for other hormones like corticosteroids (before 10 am) and growth hormone and IGF (around 10 pm, IF asleep). (Yes, that's an "am" for corticosteroids.) It's probably true for other body functions as well. In poultry, chick growth is enhanced by controlling the number of hours of brightness and darkness.

So the "1:30 am" time may not really be the actual time melatonin is released, but rather the "so many hours" after sunset, which is definitely affected by our lighting after sunset. Shifting between real time to daylight savings time may even have its effects as well.

I also don't know if it's a function of darkness or deep sleep, but circulation is also similarly subject to diurnal cycles. During the hours after midnight, circulation is shifted to the skin, away from internal organs, which is why chemo is best given in those hours (to "bypass" liver, kidneys or bone marrow). Of course, circulation continues throughout the body, but the blood flow -- amount -- is not the same throughout the day in various organs or regions of the body. In Chinese t'ien hsueh or dim mak, striking certain body points at particular times of the day can increase the killing effect of such strikes, indicating diurnal cycles of ch'i or qi.

Gerry

Can you point to a credible source for this information? (As you can see, I should be getting to bed earlier.)

I read or heard this years ago, Gerry, and why I stopped
sleeping with a light on in my bedroom. Also why I began
going to bed earlier.
It used to take me forever to get to sleep - I think it was
because I missed my 'sleeppy time', that inner clock thing.
No longer any problems.

Back in the 40's-50's, they sold light-proof satin
"goggles" that you would sleep with. Supposedly
made you more beautiful/handsome and gave you
more restful sleep.

Maybe they're still avail.

H

Oh yes, they still sell them, but they never stay on my head as I naturally toss 'n turn.

I don't have the references around right now.

The corticosteroid thing is a "standard textbook" item because administration of extraneous corticosteroids is recommended to be in the morning before 10 am to best imitate the body's cycle.

I came across the growth hormone/IGF thing from bodybuidling mags. I don't know how credible you would think these are, but I've found pretty deep biochemical/physiological stuff in their pages during the time that my brother bought a lot of them.

As for the melatonin secretion, I think the articles in the Journal of the National Cancer Institute provide the proofs of the cycle, if not the effectivity against cancer (contrary articles about the latter).

From the introduction of this study: Eva S. Schernhammer, Francine Laden, Frank E. Speizer, Walter C. Willett, David J. Hunter, Ichiro Kawachi, and Graham A. Colditz. Rotating Night Shifts and Risk of Breast Cancer in Women Participating in the Nurses' Health Study J Natl Cancer Inst 2001; 93: 1563-1568:

https://jncicancerspectrum.oxfordjour...nci;93/20/1563

The studies referred to (1 and 2) are:

Gerry

It sounds, then, like if you're chronically a night worker, your risk increases. It doesn't sound like you're at risk if you have occasional or even more than occasional insomnia.

Ruby, I have done a book report with my son about Rythem, (it was way above his head) and everything Gary said is right. I do not want to waste my time to go dig out the books we read for this report, but I do remember that the experiments were done in underground rooms where the subjects had no way of knowing the time of day, whether it was day or night, and they were tested on a number of things, including blood pressure, heart rate, hormones etc. and there was a rythem to things according to the time of day, even if the subjects were not aware of the time.

What Gary is saying is well tested and documented, you do your own research on your own time, it is out there.

Josy

Yes, ma'am.

I can easily see how if someone had a variable work schedule, sometimes working nights and sometimes days, how this could affect their system.

But if someone were working underground, with a fixed work and sleep schedule, I would expect that in time the body would adjust. Similar to jet lag.

I thought your body should adjust too, it just makes sense that it should. However certain things were set to go with the rythem of your body no matter what, it said it is like having a little clock inside your body and things run according to that clock.
I am trying to remember how long the subjects stayed in this location, which should make a difference, but it is not coming back to me...

Josy

I have a question: What if the sun doesn't set? For example when you live in Lapland during the arctic summer?

I must confess I don't believe a word of this story. I usually don't go to sleep before 3:30 a.m. And if I get sleepy during the daytime, I just lie down (anywhere) and drop off to sleep right away.

But, of course, if you're selling goggles...