The response of normal men and women to changes in their environmental temparatures and ways of life

Abstract

Sudanese men and women were flown to Cambridge in the winter of 1966/67 and at once began to take part in an experiment there lasting for 8 days with a corresponding number of British subjects. The Sudanese conformed to the British way of life. Time was provided for relaxation and exercise and the intakes and expenditures of water, salt and energy were measured. The British party were flown to Khartoum in the spring of 1968-not, for political reasons, as was originally planned in June 1967. They matched up again with the Sudanese subjects and adopted the daily routine of the latter while a similar programme of relaxation exercise and measurements was being carried out. The dry-bulb temperatures out of doors in England ranged from - 5.6 to 12.5 $^\circ$C but the rooms were warmed. The dry-bulb temperatures ranged from 14.8 to 38.7 $^\circ$C in Khartoum and none of the rooms were cooled. The food in Khartoum provided more protein and less salt than in Cambridge. The subjects ate more and expended more energy in Cambridge than in Khartoum and they also tended to gain weight, particularly the Sudanese. The British food intakes were considerably lower in Khartoum and, in spite of expending less energy, the subjects lost weight. To live the lives they did the British males had an obligatory water expenditure of around 2223 ml/day in Cambridge and 2920 ml. in Khartoum; the figures for the Sudanese were 2278 and 3381. All the subjects would have required about 7 to 8 g of sodium chloride/day in Khartoum to make their food palatable and to provide for the obligatory losses. The women ate less, expended less energy and had considerably lower obligatory losses of water and salt than the men. Neither the British nor the Sudanese showed impaired ability to perform arithmetic or prolonged vigilence tests in their unaccustomed environment. The Sudanese were less cautious than the British in that they made more false reports of signals in the vigilance task.