Circadian rhythms and alternating work schedules
As discussed in chapter 5 of Psychology: From Inquiry to Understanding (Lilienfeld) a circadian rhythm is a variety of human physiological processes that occur on roughly a 24-hour cycle. Also known as our "biological clock," this phenomenon includes regulation of sleep, hormones, body temperature, etc. Individuals who work alternating work schedules or predominately night shifts are known to have health issues because of the interference of circadian rhythms.
One factor in particular are light/dark cues that tell our subconscious when it is "bedtime" or "time to wake up." This process is partly regulated by the hormone melatonin; levels of melatonin are greater after dark and bring about a sense of sleepiness. This regulatory process is altered for people who work night shifts and therefore need to sleep during the daytime. This article discusses sleep disorders associated with circadian rhythms and shift work.
As I am sure many people have experienced, jet lag is a real issue, not just a myth to explain tiredness after a vacation. Individuals who travel a lot for work need to re-train their bodies to ignore certain bodily cues that tell them when to sleep, etc. As discussed in the article, there are various therapies used to treat these types of disorders. Most are based on training the body to get tired at a particular point by using bright lights during the work shift and pitch black environments during times of sleep.
I have concluded that there must also be a circadian rhythm associated Friday and Saturday nights that cues college students to not get sleepy and instead have the desire to party...