States of Consciousness: Part I

Sleep occurs in a cycle known as the circadian rhythm, which are internally generated patterns of body functions such as hormonal signals, sleep blood pressure, and body temperature. These functions vary over a twenty-four hour period. Even in an isolated environment that prohibits outside indicators such as day and night, windows and clocks, the circadian rhythm still operates and signals when it is time to sleep and time to awake.

In order to maintain circadian rhythms, it is important to be exposed to light. Light has the ability to keep the internal clock in sync. This is most notably observed with people whose profession deals with health care, or people who work as police or as airplane pilots and flight attendants. They usually are working in a profession that requires extended working hours, working through the night, and experiencing jet lag. Light therapy often works to adjust the discomfort of offset hours and correct the errors caused by inattentiveness. Nevertheless, it is important to remember that there is no instant cure for sleep exhaustion.

Jet lag is a phenomenon experienced during flight travel that causes exhaustion and disorientation. A good example of jet lag would be flying from Portland, Oregon, to Santiago, Chile, because the trip takes roughly twenty-four hours to complete. During the trip, sleep is sparse because of flight changes and continuos activity inside the cabin. Upon arrival in Santiago, one would find one's self with little sleep and a circadian rhythm offset by a six-hour time difference. (The difference in hours is dependent upon the time of the year.) It is said that a combination of light therapy and melatonin supplements can help remedy the resulting sleep imbalance.

There are five stages of sleep, which fall into two categories: REM and NREM sleep. When we first fall asleep, we enter the first stage of NREM (non-rapid eye movement) which on an EEG shows rapid but low amplitude brain waves gradually increasing in amplitude and slowing down in frequency. In the stages three and four, delta waves can be seen which are low frequency, high amplitude waves. REM sleep is the final phase (often called paradoxical sleep due to the rigidity of the body during this phase) where dreams are more intense and last a greater duration.

Some believe in a simple explanation as to why we sleep saying that we sleep because we are tired and that sleep is a type of remedial function for the body and mind. The only problem with this explanation is that none have been able to describe exactly what sleep remedies. The circadian theory can explain the mechanisms of sleep but not why we sleep and perhaps no single theory ever will. Sleep has far too many functions for a single theory.

Understanding why we sleep might shed a light on the phenomenon of sleep disorders. A very well known sleep disorder, although not very common, is narcolepsy. Those who suffer from this disorder tend to fall asleep abruptly and sometimes at inappropriate times such as while operating machinery. A disorder called sleep apnea is considered to be even more dangerous due to its ability to inhibit airflow into the sleeper for brief moments causing choking and sometimes even death. They say that about one in five people experience this disorder. Another disorder and possibly the most common is insomnia, which is a disorder that aggravates sleeping habits, thus causing the afflicted individual to have problematic sleep or an inability to sleep. Night terrors is a disorder that occurs in NREM, usually stage four, and causes sheer panic and fright from a vague nightmare that can't be remembered upon awakening. Sleep walking seems to be a genetic based sleeping disorder. It occurs, as with night terrors, in NREM level four where the afflicted wander in sleep as if with a purpose.