Two early signs of dehydration are thirst and dark-coloured urine. This is the body's way of trying to increase water intake and decrease water loss. Other symptoms may include: 1  dizziness or light-headedness. 2  headache. 3  tiredness. 4  dry mouth, lips and eyes. 5  passing small amounts of urine infrequently (less than three or four times a day).
Diurnality is a form of plant or animal behavior characterized by activity during the day, with a period of sleeping, or other inactivity, at night. The common adjective used for daytime activity is diurnal. The timing of activity by an animal depends on a variety of environmental factors such as the temperature, the ability to gather food by sight, the risk of predation, and the time of year.
Diurnal temperature variation. In meteorology, diurnal temperature variation is the variation between a high temperature and a low temperature that occurs during the same day.