If you suffer from insomnia, or just aren’t getting as many hours in bed as you should be each night, you are well aware of the immediate effects on your body the next day.
Writing for the New York Times, Professor Richard A Friedman of the Cornell Medical College, explains that clinicians have long known there is a link between getting the right dose of sleep and sunlight at the right times of day to positively impact your mood.
We have all experienced how a rainy day can make us feel disproportionately miserable.
But more recent evidence shows that travelling through time zones and throwing your circadian rhythm (the body’s internal clock) out of balance, can induce specific mental health problems, not just make us snoozy.
Citing a study from the 1980s, Friedman says that the direction of travel around the globe has been shown that those who traveled west generally had a higher incidence of mania while those travelling east have higher incidence of depression.
This is so well recognised that there is even a psychiatric hospital located near Heathrow, known for treating bipolar and schizophrenic travelers, some of whom are found “wandering aimlessly” through the airport terminals.
One theory as to why this occurs is that depressed people have something wrong with their bodies, which makes them release melatonin – a sleep-regulating hormone - earlier in the evening than non-depressed people.
And this release of melatonin is thrown out of kilter in everyone, not just those with underlying mental health problems, by irregular sunlight exposure during long haul flights.
This is good news for passengers looking to treat jet lag, as Friedman says: “Now you know the fix for jet lag: travel east and you’ll need morning light and evening melatonin [sleep regulating hormone] go west and you’ll need evening light and morning melatonin.”
But it also allowing a new way to potentially treat mental illness.
As a result of the findings researchers have developed a treatment called chronotherapy, which alters the circadian circadian rhythm.
This therapy involves exposure to bright lights at progressively earlier times in the morning, which should make it easier to fall asleep earlier. They also make patients avoid too much light in the evening, especially the blue light that smartphones and computers emit.
It is hoped that this altering in light, seen in flying, can manipulate people’s responses to a lack of sleep. But it is not yet known whether chronotherapy will prove as widely effective as conventional antidepressants for serious depression, says Friedman.