Experimental Evidence is Still Lacking🔬
Experimental Evidence is Still Lacking🔬
⭐️ Opinion: that's good thing.
There's a thread in research about circadian disruption that presents an interesting dilemma. To illustrate, I'm going to use a recent review about circadian dysfunction in autism spectrum disorders (ASDs)1.
Answering the question of “does circadian disruption cause”…
Here are some direct quotes from just the first two pages of this circadian dysfunction and autism paper that exemplify the issue:
...the dysfunction of the circadian timing system may be associated with ASD and its pathogenesis...
...circadian dysfunctions have been linked to an increasing number of human diseases including metabolic syndromes, cardiovascular diseases, diabetes, and cancer...
...anomalies in timing have been observed in neurological and psychiatric diseases including seasonal affective disorders, bipolar disorder, and schizophrenia,...
...the disruption of daily activity rhythms is often associated with or even precedes underlying pathophysiological changes in the brain...
I see this kind of passive and hedging language all over.
Here's the punchline from this paper’s conclusion:
...experimental evidence demonstrating that circadian disruption can lead to neurodevelopmental disorders is still lacking...
Why is Evidence Lacking in Circadian Research?
What they don't say here is that there is a specific reason for that evidence to be, and likely remain, lacking.
Designing an experiment that caused neurodevelopmental disorders in participants would be terrible!
Thanks to something called ethics, scientists can't design studies that cause harm to (human) participants.
If we can't design in a double-blind way that would prove/disprove causality, we can't know for certain what causes what.
So instead, here are some common workarounds:
try to draw inferences from animals (often to gory ends for the lab critters)
study human subjects that already have the condition of interest
use correlational human data
Circadian Disruption’s Relationship to Mental Health
The mental health article I have been sharing lately explains the challenge of interpreting human data pretty well:
Altered circadian rhythms are commonly reported among individuals with several psychiatric disorders, including major depressive disorder (MDD), bipolar disorder (BD), anxiety, and schizophrenia (SZ). However, the nature of the relationship between circadian rhythm disruption and psychopathology is poorly understood. The vast majority of clinical data are correlational. Thus, it remains unknown whether the relationship reflects:
(1) causation in which circadian disruptions predisposes individuals to developing mood disorders,
(2) causation in which the manifestation of mood disorder leads to circadian disruption, or
(3) an absence of causation in which the association between circadian disruption and mood disorders reflects commonalities in underlying physiological processes.
Proof of Effectiveness is Better than Proof of Causality
The good news is we have a lot of data about how, whatever the inital cause, resynchronizing the rhythms makes things better!
For example, ASD children may sleep better at night and act better in the day following parental education in sleep hygiene2.
Enforced darkness and blue-blocking glasses can calm manic episodes in bipolar disorder3.
Changing food timing can reverse epigenetic markers for obesity and metabolic disorders4.
And so on.
Research Chronotherapies for Yourself
So, experience confirms we don't need to know "the causes" of all these weird modern illnesses to help.
To learn more about this, you can search any condition that concerns (or interests) you, plus "chronotherapies."
By the way, sleep hygiene, though no longer taught since about 2014, showed that proper light, temperature, and sound are key to good sleep.
Is this any surprise?
As we know, these are the 3 most powerful circadian cues in the ambient environment!
I hope this is inspirational to you!
When I started searching for answers about the mysterious conditions I used to suffer from, I had no idea how far-reaching my education would be.
Who knows where you might end up as you explore this path!
There is a whole world of circadian knowledge unfolding, and all of it comes back to the point that we need natural cycles for our wellbeing.
In particular, as a society there are 3 things we know we need to address together:
Light. We need to reduce our reliance on electrical light. It is not bright enough during the day, and it is too bright at night5.
Temperature. We need to cool our bedrooms down at night (and for the frugal, maybe warm them up)6.
Sound. We need to address traffic noise (and no, switching to electric engines won't cut it)7.
That's all for today, but you can always review past posts in the archive.
There are also links to the full-texts of the papers cited in the footer of this post, just click the citation.
And I will send more natural living research & analysis in my upcoming emails.
Hope you have a great day!
🧡
NIKKO