Public Health surveillance systems can be passive or active. A passive surveillance system consists of the regular, ongoing reporting of diseases and conditions by all health facilities in a given territory.
Insomnia. The glow of the alarm clock is all too familiar. Insomnia refers to an inability to fall asleep or stay asleep, or a tendency to wake up too early or experience poor sleep. 1  Definition. 2  Symptoms. 3  Causes.
Although it is a sleep disorder on its own, insomnia can also be associated with various other medical conditions that trigger a disturbance in one or more body systems, rhythms or patterns. In other words, sleeplessness can cause or be caused by other mental and physical ailments.