Hyperphagia is defined as excessive ingestion of food beyond that needed for basic energy requirements. Ingestion may occupy unusual amounts of time. Eating may be obligatory and disrupt normal activity. In contrast, bulimia usually occurs surreptitiously in defined episodes and is terminated by abdominal pain, guilt or sleepiness.

Hyperphagic conditions may occur in association with central nervous system (CNS) disorders including gangliocytoma of the third ventricle [99], hypothalmic astrocytoma [100], Kleine-Levin Syndrome [101, 102, 103], Froehlich’s Syndrome [104], Parkinson’s Disease [105], genetic disorders including Praeder-Willi Syndrome (deletion of the long arm of chromosome 15) [105, 106, 107, 108], major psychiatric disorders including anxiety, major depressive disorder [44], depressive phase of bipolar disorder [109], seasonal affective disorder [110, 111, 112], and schizophrenia [113, 114], psychotropic medication, including delta-9 tetrahydrocannabinol [109], antidepressants and neuroleptics [115, 116] and sleep disorders including sleep apnea [117]. Recent evidence evaluating episodic hormone secretion during sleep in Kleine-Levin Syndrome reveals an abnormality in the hypothalmic regulation of pituitary hormones [114].

Hyperphagia Associated with Sleep Disorders

Sasson [117] has noted that in patients with sleep apnea who are somnolent during the day, there is obligatory eating to induce alertness, thus reducing daytime drowsiness. This hyperphagia has produced markedly increased body weights in such patients. Binge eating behavior and morning anorexia have been described by Stunkard [118] in the context of a "night eating" syndrome, suggesting a component of sleep disturbance. In the Kleine-Levin Syndrome [101] hyperphagia is associated with hypersomia.

Recent evidence evaluating episode hormone secretion dorms sleep in Kleine-Levin Syndrome reveals an abnormality in the hypothalamic regulation of pituitary hormones [119].

Hyperphagia Associated with Psychiatric Disorder

Hyperphagia may occur in psychiatric disorders such as depression, anxiety [44] and schizophrenia [113]. A subgroup of patients with anxiety overeat and gain weight [44] as do some patients with unipolar depression [44] and the depressive phase of a bipolar disorder [119].

Rosenthal [110, 112] reported patients with seasonal affective disorder who appeared to have an atypical depression with hypersomnia, compulsive hyperphagia, carbohydrate craving, and weight gain, a syndrome which recurred beginning in the fall of the year and lasting through the winter months, with resolution during the increasing daylight hours in spring and summer.

Lyketsos et al. [113] noted that schizophrenic women were found to give too much time and thought to food and to be preoccupied with food or they were perceived by nursing staffs as becoming anxious and greedy at mealtimes. In addition, it was noted that 60 percent of schizophrenic women were overweight, in contrast to 33 percent of schizophrenic men. The hyperphagic effects of phenothiazines appear to have only a minor role in increasing appetite.

Arieti [114] noted unusual eating patterns and described a terminal stage of schizophrenia wherein food selectivity was lost and indiscriminate eating, including pica (non-nutritive eating) occurred. A number of medications, including psychotropics and antidepressants, specifically amytriptiline [115, 116], neuroleptics [115] and many other medications [115] increase appetite. Furthermore, Vaupel and Morton [109] noted that a number of abused substances, such as marijuana (Delta-9 tetrahydrocannabinol) increased appetite. Eating disorder syndromes may be found in increasing association with substance abuse with more extensive clinical and diagnostic delineation.