One study has shown that up to 69% of patients find lightbox treatment inconvenient, and as many as 19% stop use because of this.Dawn simulation has also proven to be effective; in some studies, there is an 83% better response when compared to other bright light therapy. When compared in a study to negative air ionization, bright light was shown to be 57% effective vs. dawn simulation 50%. Patients using light therapy can experience improvement during the first week, but increased results are evident when continued throughout several weeks. Certain symptoms like hypersomnia, early insomnia, social withdrawal, and anxiety resolve more rapidly with light therapy than with cognitive behavioral therapy. Most studies have found it effective without use year round, but rather as a seasonal treatment lasting for several weeks, until frequent light exposure is naturally obtained.Light therapy can also consist of exposure to sunlight, either by spending more time outside or using a computer-controlled heliostat to reflect sunlight into the windows of a home or office. Although light therapy is the leading treatment for seasonal affective disorder, prolonged direct sunlight or artificial lights that dont block the ultraviolet range should be avoided, due to the threat of skin cancer.The evidence base for light therapy as a preventive treatment for seasonal affective disorder is limited. The decision to use light therapy to treat people with a history of winter depression before depressive symptoms begin should be based on a persons preference of treatment. Medication
SSRI (selective serotonin reuptake inhibitor) antidepressants have proven effective in treating SAD.
Several medical definitions of delirium exist (including those in the DSM and ICD-10), but the core features remain the same. In 2013, the American Psychiatric Association released the fifth edition of the DSM (DSM-5) with the following criteria for diagnosis:
A. Disturbance in attention and awareness. This is a required symptom and involves easy distraction, inability to maintain attentional focus, and varying levels of alertness. B. Onset is acute (from hours to days), representing a change from baseline mentation with fluctuations throughout the day
C. At least one additional cognitive disturbance (in memory, orientation, language, visuospatial ability, or perception)
D. The disturbances (criteria A and C) are not better explained by another neurocognitive disorder
E. There is evidence that the disturbances above are a "direct physiological consequence" of another medical condition, substance intoxication or withdrawal, toxin, or various combinations of causes

Signs and symptoms
Delirium exists as a stage of consciousness somewhere in the spectrum between normal awakeness/alertness and coma. While requiring an acute disturbance in consciousness/attention and cognition, delirium is a syndrome encompassing an array of neuropsychiatric symptoms.The range of clinical features include: poor attention/vigilance (100%), memory impairment (64–100%), clouding of consciousness (45–100%), disorientation (43–100%), acute onset (93%), disorganized thinking/thought disorder (59–95%), diffuse cognitive impairment (77%), language disorder (41–93%), sleep disturbance (25–96%), mood lability (43–63%), psychomotor changes (e.g. hyperactive, hypoactive, mixed) (38–55%), delusions (18–68%), and perceptual change/hallucinations (17–55%). These various features of delirium are further described below:

Inattention: As a required symptom to diagnose delirium, this is characterized by distractibility and an inability to shift and/or sustain attention.