The fluctuations in the alertness, energy and moods over the course of a day are closely related to changes in underlying bodily processes. Daily cycles occur in the production of various hormones, core body temperature, blood pressure, and several other processes. For many persons, these fluctuations are highest in the late afternoon and evening, and lowest in the early hours of the morning. Large individual differences in this respect exist. So the pattern varies greatly across persons. Circadian rhythms seem to shift with age. As people grow older, their peaks often tend to occur earlier in the day.
The cyclic fluctuations in basic bodily functions and in our subjective feeling of alertness are related to task performance. In general, people do their best work when their body temperature and other internal processes are at or near their personal peaks. However, this link appears to be somewhat stronger for physical work than for mental task.
It seems reasonable to suggest that we possess some internal biological mechanism to regulate such changes. We possess one or more biological clocks that time various circadian rhythms. It has been postulated that one structure–the suprachiasmatic nucleus (SCN), located in the hypothalamus–plays a key role. It appears that individual cells in this structure “tick”–keep track of time.
The SCN is not a totally sealed clock, unresponsive to the outside world. It responds to light. Morning light resets our biological internal clock, synchronization is required, because our biological clock (and that of many other species) seems to operate on a twenty-five-hour cycle. If it is not reset, our biological clock would go farther and father. This twenty-five-hour cycle has been observed in research studies in which volunteers have lived in dark caves ( without sunlight). In these conditions, most persons shift towards a “day” of twenty-five-hours.
The mechanism that governs long-term biological rhythms has also been identified. A structure in the brain-the pineal gland seems: to play an important role. The pineal gland sits on the top of the mid brain. It secrets a hormone known as melatonin. The pineal gland is connected to the SCN and secretes melatonin in response to input from the SCN. Melatonin has far-reacting effects influencing many structives in the brain and regulating the production of hormones, and affecting many physiological processes. Melatonin is secreted mostly at nights. When nights are long, larger amount of melatonin are secreted. Higher melatonin levels seem to play a role in triggering hybernation in many species. When days get longer, less melatonin is secreted and many species become active and seek mates during summer and spring.
A major implication of circadian rhythm is the concept of morning person vis-à-vis night person. Morning people feel most alert and active in the day, whereas night people experience peaks in alertness and energy in the afternoon or evening. Studies comparing morning and evening persons indicate that morning people have a higher overall level of adrenaline than night people. They also operate at a higher level of activation. Similarly morning people experience peaks in body temperature earlier in the day than night people.
The difference in alertness and bodily states translate into important effects on behaviour. Morning persons earn higher grades in early morning classes, while night persons receive higher grades in classes offered later in the day. If you are a morning person, try to take your task at that time; if you are a night person, it is better to undertake afternoon or evening assignment. The given box would help you to make self-diagnosis with respect to your rhythm.
Are You a Morning Person or a Night Person?
Answer each of the following items by circling either “Day” or “Night”.
1. I feel most alert during the Day Night
2. I have most energy during the Day Night
3. I prefer to take classes during the Day Night
4. I prefer to study during the Day Night
5. I get my best ideas during the Day Night
6. When I graduate, I plan to find a job during the Day Night
7. I am most productive during the Day Night
8. I feel most intelligent during the Day Night
9. I enjoy leisure-time activities most during the Day Night
10. I prefer to work during the Day Night
If you answer “Day to eight or more of these questions, you are probably a morning person. If you answer “Night” or eight to more, you are probably a night person.