I am the sort of person who can more easily stay awake until eight in the morning than wake up at eight in the morning. I go to bed late, and wake up late (at least when I don’t have any where to be). However, one of my roommates likes to go to bed before 10:30 and wakes up at 9:00 nearly every morning. Putting aside the fact that I don’t understand why anyone would willingly get themselves out of bed early in the morning when they could be asleep or how they manage to be friendly, productive people before noon hits, I do wonder how sleeping times affect people’s overall health. Now, my roommate is a very fit, healthy person anyway because she eats well and works out, however I wonder if her sleeping habits have positively affected her as well.
So the null hypothesis is that sleeping times do not have any real, significant affect on people’s health, and so it does not actually matter what time you may decide to go to bed. The alternative hypothesis, on the other hand, is that sleeping times do in fact affect health in some way, and it does matter when we go to sleep. See, I’ll get nine hours of sleep a night and yet still feel exhausted the next day. I’m almost convinced this is because I went to bed at two in the morning and woke up at eleven. I had read things about this before, and I knew it had something to do with circadian rhythms and the like, however I did not know enough to fully understand. Circadian rhythms determine if we prefer to stay up late or wake up early. This is called our chronotype.
First off, according to this study, whether we are “morning” or “night” people, so to speak, has in part to do with our DNA. The study, called a genome-wide association study (or GWAS), was done by 23andMe, a consumer genetics company. A sample of nearly 90,000 people submitted their DNA through spit samples, making this one of the largest studies about circadian rhythms done using human subjects. The people in the sample were narrowed down from about 135,00 who had taken a survey asking simply if they thought of themselves as night people or morning people. Those who answered neutrally were removed from the experiment. The study’s intention was to find links between various versions of genes and traits specific to being a “morning” or “night” person. It found connections between fifteen different versions of genes, of which seven were close to genes already known to be linked to circadian rhythms. The nearness of the genes indicates that they have similar functions. What I took from this is that, with more research and more studies, scientists could eventually prove with near certainty that being a morning or night person has a direct causation with our DNA. Unfortunately, however, this topic does seem to suffer from the file drawer problem. I believe only the studies that got the desired results have been published.
Now, this study did indicate that what I had previously stated in my alternative hypothesis is correct. Sleeping times do in fact affect our bodies and our health. People who described themselves as “night” people were close to two times as likely to suffer from insomnia, and nearly two-thirds as likely to be diagnosed with sleep apnoea. “Morning” people were less likely to need more than eight hours of sleep, to sleep walk, or even to sweat while they are asleep.
It also showed that “morning people” usually had a lower body mass index than “night people”, and that they were less likely to have depression as well. However, though the two things are correlated, scientists could not find a causation between BMI or depression and being a morning person. Basically, we can’t say that being a night person causes depression, or causes a person to be overweight.
Another study, published in the Journal of Clinical Endocrinology & Metabolism, was done by Korean researchers with a sample group of 1,620 middle-aged men and women and showed very similar results. As in the above study, they asked their participants to answer a survey to indicate if they thought of themselves as night or morning people. Variables like smoking habits, exercise frequency, alcohol consumption, hypertension, blood pressure, BMI, and other such things were measured beforehand and taken into consideration. The results of this study showed that men who were classified as night people were more likely to have diabetes. And women classified as night people high blood sugar levels and excess body fat around the mid-section. The scientists were unable to find a sure mechanism, however they did state that it was likely these metabolic affects were quite likely related to the consumption of calories after eight at night and being exposed to more artificial light.
Based on the research done by these two groups of scientists, I think we can safely say that sleep times do affect our health; specifically, going to bed later at night affects it negatively. I, personally, would love to do what is best for my health and go to bed earlier. However, being an over-worked college student does not really allow for that.