There is abundant evidence that the sleep disruption that comes with shiftwork has long term effects on health. So evidence jet lag influences neurodegenerative diseases isn't surprising. What is unexpected is evidence interfering with sleep/wake cycles by changing timezones might actually be protective. The research has only been done on fruit flies so far, so don't start booking flights just yet, but further studies are planned.
People with neurodegenerative diseases often have wonky circadian clocks, undermining their ability to fall asleep at appropriate times. Indeed, Professor Ravi Allada of Northwestern University explained in a statement: “We have long known that a disrupted clock is an early indicator of neurodegenerative disease. In many cases, sleep disruption precedes any other symptom. But we didn’t know whether the circadian disruption is a cause of the disease or a consequence of the disease.”
Allada investigated using fruit flies with Huntington's disease. Although much rarer than diseases like Parkinson's, Huntington's has been heavily studied by neuroscientists because its relative simplicity could make it a gateway to understanding more complex conditions.
Normally, fruit flies wake and sleep on a 24-hour cycle, but Allada said, “In the Huntington’s model, there is no rhythm. The flies wake up and fall asleep all the time.”
Allada put flies with Huntington's disease genes in cages where lights went on and off over a 20-hour cycle, leaving them with permanent jet lag. Other flies got more radical treatment, with a deliberate mutation made on to a circadian clock-setting gene.
Instead of making Huntington's worse, as expected, both sets of flies experienced partial protection, Allada announced in Cell Reports. Their brains accumulated fewer proteins associated with Huntington's disease, and their neurons lived longer, relative to controls.
“It seems counterintuitive, but we showed that a little bit of stress is good,” Allada said. “We subtly manipulated the circadian clock, and that stress appears to be neuroprotective.”
Allada sought another circadian clock-control gene that might explain the mystery, and focused on one that has an additional role in influencing protein folding. This aroused suspicions, since protein misfolding is thought to play a big part in many neurodegenerative diseases.
By removing this gene from Huntington's flies, Allada again unexpectedly reduced the disease, measured both by protein build-up and brain cell death.
Humans and flies are very different, of course, but circadian clock genes are remarkably similar between us.
Before tackling the tricky question of how to run similar tests on humans, Allada plans to see whether inducing jet lag is also protective for fruit flies with genes for Alzheimer's disease.
Targeting the proteins Allada has identified is more likely to make medical sense than deliberately giving people jet lag to ward off degeneration. Still, the next time you emerge bleary-eyed at dawn on a new continent you can comfort yourself that you may be helping keep your brain functional.