No abstract

In a study of lifestyles and health of the adult population of some Oxfordshire villages, data were collected upon the usual sleep duration and quality, smoking and drinking habits of 725 men and 759 women. A strong negative association has been found between cigarette smoking and sleep duration on both sexes, and between alcohol consumption and sleep duration in men. There is no equivalent association between drinking or smoking and reported poor quality sleep. While these findings do not prove a causal relationship, the absence of complaints of poor quality sleep among the smokers and drinkers suggests that these habits are not simply the correlates of underlying psychological problems leading to insomnia.

No abstract

A study has been made of three neighbouring populations living at 1500, 3000 and 3700 m in the northern Simien of Ethiopia. The environments of these populations not only differ in many climatic elements, but also probably in nutritional factors and exposure to infections. The growth and physique of the people vary with altitude and the lowlanders (at 1500 m) tend to have a more linear body build. Differences in chest dimensions can be related to functional differences in respiratory physiology, since the highland groups, both male and female, have larger forced expiratory volumes and forced vital capacities as compared with the lowlanders. The relationships between these measures of respiratory function and age, stature and weight also tend to be dependent on altitude, but in all the Ethiopian groups there is a closer relationship between body weight and respiratory capacity than in other populations. This distinctiveness is probably due to the characteristics of Ethiopian physique. A slight polycythaemia and elevated packed cell volume are evident in the highland groups but, unexpectedly, there is some evidence that at least at the time of the expedition the haemoglobin concentrations were lower. The highlanders also show a raised systolic blood pressure. Blood-group and demographic data suggest that the various populations are probably genetically very similar, and the findings are discussed in terms of physiological and developmental adaptability.

No abstract

The influence of sex, age, and socioeconomic conditions on specific grip strength of 6-18-year-old individuals was studied among 1,704 males and 1,956 females belonging to the so-called "Cape Coloured" community in the western part of South Africa. Half of the participants of both sexes came from communities in the Greater Cape Town area where living conditions are comparable to those of middle-class First World communities (high SES). The other half came from the poorest rural communities of Klein Karoo (low SES). Arm circumferences, triceps skinfold thickness, and grip strength of the right and of the left hand were greater in individuals from high SES at all ages. Females within each SES group had skinfolds thicker than males, especially at older ages, and were weaker. Specific grip strength (SS), estimated as grip strength per unit area of cross section of the fat-free arm, increased with age in each group, was greater in males, and was significantly lower in low SES groups, than in the high SES ones, especially during and after puberty. It seems that SES difference in SS will persist into adulthood. Sexual differences in SS can be attributed to hormonal differences; while the SS increase with age and the difference between SES groups find no clear explanation in current theories of muscle growth and development. Since the speed of neuromuscular reaction observed in our participants is slower among low SES individuals, it seems that the difference in neuromuscular control of strength may be responsible for our findings. Differences in muscle metabolism and hormonal regulation must also be considered.

Both Frankenhaeuser and Karasek have put forward models describing how job demand and control influence epinephrine and cortisol levels. These models were tested in a sample of 53 women and 51 men in a variety of occupations. They were studied over one rest day and two working days. Subjects reported their perceived demand and control and their mood on each day, as well as providing urine for assessment of urinary excretion rates of epinephrine and cortisol. In men, but not women, epinephrine levels were higher on the working days than on the rest day, and demand was found to covary positively with epinephrine, supporting Frankenhaeuser's model with respect to epinephrine variation in men. However, cortisol levels were not elevated on working days compared to the rest day, and no relationship between job control and cortisol was seen which is in contradiction of Frankenhaeuser's model with respect to cortisol variation. There was some suggestion that demand was most strongly associated with elevated epinephrine in men when job control was low in accordance with Karasek's model, but there was no evidence for such an effect with respect to cortisol.

An analysis has been undertaken of the comparative magnitudes of the within-population variability in stature and body weight as reported in the recent literature. The distributions of the variability have been investigated for patterns related to latitude, altitude, 'affluence' and the mean value of the measurements. It is shown that differences in stature variability are substantially explained by differences in mean stature only. This however, is not the case with weight variability where, in addition to the mean, there is evidence of independent effects of affluence, altitude, and especially latitude. In most populations the weight of females is more variable than that of males. This is considered to be due to their greater amounts of fat, and differing levels of fat may also explain much of the geographical patterns in weight variability.