Sleep disturbance is a general term that doctors use to describe any difficulties relating to the ability to fall asleep or stay asleep throughout a sleeping session. Some people with these disturbances have problems severe enough to qualify as official sleep disorders, while others do not. Schizophrenia is heavily linked to sleep disturbances, and for a long time mental health professionals have viewed such problems as a symptom of schizophrenia. However, current evidence indicates that sleep disturbances may actually make changes in normal brain function that trigger the onset of schizophrenia. Sleep Basics Human sleeping patterns are based on circadian rhythms, the natural day\/night sleep cycles developed throughout our species\u2019 evolutionary past. These rhythms are established and maintained by a clock-like mechanism inside a part of the brain known as the hypothalamus. Any given sleeping session contains two distinct phases, called REM (rapid eye movement) and NREM (non-rapid eye movement) sleep. Throughout sleep, the brain repeatedly cycles through these phases, as well as through individual stages contained within the larger phases. Proper rest for a human being depends upon the consistent maintenance of his or her circadian rhythms, as well both the REM and NREM phases of sleep. Sleep Disturbance Basics Generally speaking, sleep disturbances occur when there are disruptions in a person\u2019s circadian rhythms, or in a person\u2019s REM or NREM sleep. Circadian rhythm-related problems include jet lag and two conditions called advanced sleep phase syndrome (which involves falling asleep and waking up abnormally early) and delayed sleep phase syndrome (which involves falling asleep and waking up abnormally late). Disruptions in REM or NREM sleep can lead to problems that include unusual fatigue, daytime sleepiness and difficulties with mental focus or concentration. The lack of sleep caused by sleep disturbances is often referred to as sleep deprivation. In its advanced form, sleep deprivation can lead to memory loss, hallucinations and a confused mental state. As indicated previously, some people with sleep deprivation have diagnosed or undiagnosed cases of verifiable sleep disorders such as insomnia, restless leg syndrome, or sleep apnea. Ties to Schizophrenia Thirty percent to 80 percent of all people with schizophrenia have significant disturbances in their sleeping patterns, according to a study published in 2008 in the journal CNS Drugs. People with relatively minor versions of the disorder\u2019s psychotic symptoms typically fall on the lower end of this percentage, while people with prominent psychotic symptoms typically fall on the upper end. The vast majority of affected individuals experience disruptions in either the REM or NREM phases of their sleeping sessions. In addition, roughly 50 percent of affected individuals also have altered circadian rhythms and don\u2019t follow a normal day\/night sleep cycle. As stated previously, mental health professionals generally view sleep disturbances in schizophrenics as a manifestation of the disorder\u2019s effects on baseline brain function. Sleep Disturbances as a Schizophrenia Cause In a study published in 2012 in the journal Neuron, a multi-institution research team examined the ways in which sleep disturbances alter normal activity inside the brain. They performed this examination by analyzing brain wave patterns in controlled laboratory experiments involving rats; rats often stand in for people in such experiments because of certain key similarities between their brains and human brains. During normal deep sleep, brain waves pass in a stable manner from the front of the brain to the back of the brain. However, under the influence of sleep deprivation, these waves destabilize and fail to pass through the brain\u2019s structures in an orderly fashion. Two key structures affected by this brain wave destabilization are the hippocampus\u2014which plays a vital role in the brain\u2019s ability to form memories\u2014and the frontal cortex, which plays an equally vital role in the brain\u2019s ability to make judgments and decisions. The authors of the study concluded that the effects of the brain wave disruptions caused by sleep disturbances strongly resemble the distortions in memory function and decision-making that occur in people with schizophrenia. They also concluded that sleep disturbances may very well act as a trigger for schizophrenia, rather than appearing in the aftermath of the disorder\u2019s onset. If this second conclusion is confirmed by future research, it may lead to significant advances in the scientific understanding of schizophrenia, as well as to new methods for predicting and preventing the disorder. It may also lead to the development of new ways to treat schizophrenia, especially certain symptoms\u2014such as memory and focusing problems\u2014that don\u2019t respond well to current schizophrenia treatments.