Normal sleep, disturbed sleep, transient and persistent insomnia

There are three fundamental principles for understanding sleep; (1) the sleeping brain is not a resting brain, (2) the sleeping brain functions in a different manner from the waking brain and (3) the activity and work of the sleeping brain are purposeful. The sleeping brain does fail and this failure is mainfest in a variety of clinical symptoms; all sleep complaints should be taken seriously and investigated. Transient insomnia is uniformly associated with objective sleep disturbances which have been documented following phase shifts of the major sleep period such as that caused by transmeridian travel. However, the degree to which the individual responds to these factors is variable. There is a consensus that sleep medications are indicated for transient and short-term insomnia. Benzodiazepine hypnotics are commonly used to induce and maintain sleep, and improve daytime alertness.