The circadian rhythms that govern how we sleep are impacted by many of the things that around us, the things that we experience, and the environment that we live in. That environment includes the light and dark cycles around us – both natural and electric.
There have been a variety of studies done throughout the years on the impact that the natural rhythms of night and day have on human bodies. There was one particularly interesting study done in 2012 on the impact of long winter days on the individuals working in the arctic.
That study found that, when deprived of light for long periods of time, many individuals maintained some semblance of a 24 hour light cycle, though some do end up defaulting to cycles that are more or less than 24 hours.
While it’s easy to think that conditions such as Seasonal Affective Disorder are simply a function of latitude, that may not be the case. Quoting from a 2005 overview of Seasonal Affective Disorder :
An estimated 10 to 20 percent of recurrent depression cases follow a seasonal pattern.3 Although a summer pattern of recurrence is possible, the predominant pattern involves fall/winter depression with spring/summer remission. In U.S. community surveys, SAD prevalence ranges from 9.7 percent in New Hampshire to 1.4 percent in Florida.4 In North America, SAD prevalence increases with latitude, but the correlation is nonsignificant in other parts of the world.
In fact, it may be that the impact late nights and long nights have on our psychology is partially a function of the mindset we have going in. Quoting from Science Nordic:
Leibowitz and Vittersø found a correlation between how far north people lived in Norway and how positively they viewed winter and winter darkness. More importantly, “Vittersø and I found that positive thought patterns in winter were related to life satisfaction, positive emotions and seeking challenges that can lead to personal growth,” Leibowitz, an American psychology student, said. Vittersø emphasizes that the study has not been published in a peer-reviewed journal, and that the correlations they found do not mean causation.
Nevertheless, he says that the study suggests what might make life easier for Norwegians during a time of year that most people don’t really like. “We who live in Norway are probably not aware that we see so much to enjoy during the winter, because it is so normal for us,” Vittersø said. “But it is probably much less common to look at winter this way elsewhere in the world.”