Both sleep disorders involve a disruption to your body’s circadian timing system. This system regulates the timing of when you sleep and wake.
The study shows that this disruption occurs in two separate groups of neurons in the brain. It also involves two different sleep stages.
Both groups of neurons are located in the “suprachiasmatic nucleus.” This part of the brain acts as a body clock. It regulates daily functions such as body temperature, hormone levels and sleepiness.
The study found that one set of neurons is closely linked with slow wave sleep. This is also called “deep sleep.” These neurons receive light information directly from the eyes. With these light and dark signals, your pattern of deep sleep can adjust to a new schedule in a couple of days.
Another set of neurons controls rapid eye movement – or REM – sleep. Most of your dreams occur during this stage. These neurons do not receive direct light information. As a result your pattern of REM sleep can be out of sync for a week or more when you cross time zones.
The researchers exposed lab rats to an artificial light-dark schedule. This simulated a trip from Paris to New York.
They also found that the time change disrupted the normal progression of sleep stages. There was an overlap of slow wave sleep and REM sleep right after the simulated jet lag. The rats also were more likely to enter REM sleep earlier than they should.
The study helps explain why it takes the body so long to adapt to a new time zone. After a long flight it typically takes about one day per time zone for your body clock to adjust to the local time.
Researcher Horacio de la Iglesia expects that the study will have a positive impact on treatments for jet lag and shift work.
"We can go back to the treatments that are believed to be effective and see where they might be acting in the circuitry of these neuron centers, then refine them to be more effective," he said in a University of Washington statement.
Image by Kossy