. propose `evening meal’ should be classed as the first food eaten after 1700 hours, which could be a `main meal’ or `snack’ if no main meal is eaten. If no food is eaten by 2000 hours, then any food after 2000 hours is classed as `after the evening meal’.31 Future understanding of NES will benefit from consistent methodology for identifying energy intake across studies and explicit definition of the `evening meal’. The extent to which individuals with evening hyperphagia, but undisturbed sleep, could be classed as NES was ambiguous based on early criteria. Current criteria now make this explicit, suggesting both evening hyperphagia and/or at least two Chaetocin solubility episodes of nocturnal eating per week’ are classed as NES. The predominance of one construct over another continues to be debated. Item response theory analysis of responses from NE questionnaires completed by 1481 individuals suggests key features to be nocturnal eating and/or evening hyperphagia, initial insomnia and night awakening, with morning anorexia and delayed morning meal less important.9 Others conclude that evening hyperphagia and nocturnal eating are the same construct and propose a continuum of severity, identifying individuals without nocturnal snacking as `NES’ and nocturnal snackers as `NES plus nocturnal snacking’.32,33 Striegel-Moore et al.34 also distinguish between evening-eaters and night-eaters, suggesting NES should be based on eating very late at night. IDENTIFICATION The absence of a consistent method for identifying NES encouraged early researchers to use various methods to establish diagnosis, including interviews, questionnaires based solely on Stunkard’s criteria and questionnaires combining other syndromes.12?4 An interview conducted by an ED specialist is now considered the gold standard diagnostic tool for NES. Symptom severity is measured with the NE questionnaire (NEQ)35 and findings supplemented using the Night Eating Symptom and History Inventory (NESHI), a 17-item interview schedule.29 The NEQ underwent several revisions and now contains 14 items and a five-point Likert scale. Validation studies on the current version were published in 2008 combining evidence from three separate NES studies.35 Study 1 examined factor structure and internal consistency, and included 1980 persons with selfdiagnosed NES who completed the NEQ on the Internet. The mean score was 33.1 (7.5). Principal components analysis was used to generate four factors (nocturnal ingestions, evening hyperphagia, morning anorexia and low mood/disturbed sleep) with a Cronbach’s alpha of 0.70. The second study in 81 outpatients diagnosed with NES found acceptable convergent validity of the NEQ with additional measures of NE, disordered eating, sleep, mood and stress. The third study compared scores from obese bariatric surgery candidates with and without NES, and found appropriate discriminant validity of the NEQ. Of 184 individuals, 19 (10.3 ) were identified with NES. Mean scores were NES 26.2 (8.1) vs AG-490 molecular weight nonNES 16.0 (6.3). The positive predictive value of the NEQ at a score of 25 or higher was low (40.7 ), increasing to 72.7 at a score of 30 or greater. The negative predictive value was high for cut scores of both 25 and 30 (95.2 and 94.0 , respectively). Other researchers have found similar cut points useful, although it is recommended that item 13 which explores awareness during NE be excluded from scoring as this is a diagnostic item distinguishing NES from sleep disorders. When item 13.. propose `evening meal’ should be classed as the first food eaten after 1700 hours, which could be a `main meal’ or `snack’ if no main meal is eaten. If no food is eaten by 2000 hours, then any food after 2000 hours is classed as `after the evening meal’.31 Future understanding of NES will benefit from consistent methodology for identifying energy intake across studies and explicit definition of the `evening meal’. The extent to which individuals with evening hyperphagia, but undisturbed sleep, could be classed as NES was ambiguous based on early criteria. Current criteria now make this explicit, suggesting both evening hyperphagia and/or at least two episodes of nocturnal eating per week’ are classed as NES. The predominance of one construct over another continues to be debated. Item response theory analysis of responses from NE questionnaires completed by 1481 individuals suggests key features to be nocturnal eating and/or evening hyperphagia, initial insomnia and night awakening, with morning anorexia and delayed morning meal less important.9 Others conclude that evening hyperphagia and nocturnal eating are the same construct and propose a continuum of severity, identifying individuals without nocturnal snacking as `NES’ and nocturnal snackers as `NES plus nocturnal snacking’.32,33 Striegel-Moore et al.34 also distinguish between evening-eaters and night-eaters, suggesting NES should be based on eating very late at night. IDENTIFICATION The absence of a consistent method for identifying NES encouraged early researchers to use various methods to establish diagnosis, including interviews, questionnaires based solely on Stunkard’s criteria and questionnaires combining other syndromes.12?4 An interview conducted by an ED specialist is now considered the gold standard diagnostic tool for NES. Symptom severity is measured with the NE questionnaire (NEQ)35 and findings supplemented using the Night Eating Symptom and History Inventory (NESHI), a 17-item interview schedule.29 The NEQ underwent several revisions and now contains 14 items and a five-point Likert scale. Validation studies on the current version were published in 2008 combining evidence from three separate NES studies.35 Study 1 examined factor structure and internal consistency, and included 1980 persons with selfdiagnosed NES who completed the NEQ on the Internet. The mean score was 33.1 (7.5). Principal components analysis was used to generate four factors (nocturnal ingestions, evening hyperphagia, morning anorexia and low mood/disturbed sleep) with a Cronbach’s alpha of 0.70. The second study in 81 outpatients diagnosed with NES found acceptable convergent validity of the NEQ with additional measures of NE, disordered eating, sleep, mood and stress. The third study compared scores from obese bariatric surgery candidates with and without NES, and found appropriate discriminant validity of the NEQ. Of 184 individuals, 19 (10.3 ) were identified with NES. Mean scores were NES 26.2 (8.1) vs nonNES 16.0 (6.3). The positive predictive value of the NEQ at a score of 25 or higher was low (40.7 ), increasing to 72.7 at a score of 30 or greater. The negative predictive value was high for cut scores of both 25 and 30 (95.2 and 94.0 , respectively). Other researchers have found similar cut points useful, although it is recommended that item 13 which explores awareness during NE be excluded from scoring as this is a diagnostic item distinguishing NES from sleep disorders. When item 13.