Night Eating Syndrome, circadian rhythms and seasonality: a study in a population of Italian university students

Sindrome da alimentazione notturna, ritmi circadiani e stagionalità: studio in una popolazione di studenti universitari italiani

GIULIA RICCOBONO1, ANGELA IANNITELLI1,2, ASSUNTA POMPILI1, CARLA IORIO1,
PAOLO STRATTA3, RODOLFO ROSSI4, GIUSEPPE BERSANI2, FRANCESCA PACITTI1
*E-mail: francesca.pacitti@univaq.it

1Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, Italy
2Department of Psychiatric Sciences and Psychological Medicine, Sapienza University of Rome, Italy
3Department of Mental Health, ASL 1, Abruzzo, ITALY
4Department of Systems Medicine, University of Tor Vergata, Rome


SUMMARY. Purpose. The aim of this research was to assess the prevalence of Night Eating Syndrome (NES) in a university student population and to clear up the relationship between NES, depression and chronotype. The relation between NES and seasonality was also investigated. Methods. The data were collected from a sample of 1136 students of the L’Aquila University, Italy. All subjects were invited to answer to the Sociodemographic Information Form and to take a self-report battery composed by four questionnaires: the Night Eating Questionnaire (NEQ), the Morningness Eveningness Questionnaire (MEQ), the Seasonal Pattern Assessment Questionnaire (SPAQ) and the Beck Depression Inventory (BDI). Results. The 5.3% of our population (60 subjects) reached the criteria for NES. The distribution of chronotypes in the sample was: Morning Type 15.3%, Intermediate 64.3% and Evening Type 20.4%. The 36.7% of the participants reaching the criteria for NES, obtained low scores on the MEQ. The data indicated that NEQ and MEQ scores are significantly inversely correlated (r=-.22; p<.01, two-tailed test). The 3.6% of our population (41 subjects) reached the criteria for Seasonal Affective Disorder (SAD) and 10.7% for subclinical SAD (121 subjects). Furthermore, the 11.7% of subjects with NES presented SAD and the 5% presented Subclinical SAD. The data demonstrated that NES and Global Seasonality Score (GSS) are significantly associated (r=.22; p<0.01, two-tailed test). Conclusions. The main finding of this study is the strong relation between NES and eveningness dimension. Our results help to clear up the literature debate about the role of eveningness dimension in the night eating, suggesting that subjects with NES present a circadian delay, not only in the food intake, but in the entire functioning. At the best of one knowledge this study is the first one to examine the relationship between NES and seasonality. This research found preliminary evidence that, similarly to the findings of previous studies in subjects with Bulimia Nervosa (BN) and Binge Eating Disorder (BED), night eating symptoms may vary significantly across the seasons; subjects with NES experience seasonal variation in their mood and in their eating patterns.

KEY WORDS: Night Eating Syndrome, seasonality, Seasonal Affective Disorder, evening chronotype, chronotype.


RIASSUNTO. Introduzione. Lo scopo del presente studio è quello di valutare la prevalenza della sindrome da alimentazione notturna (Night Eating Syndrome - NES) in una popolazione di studenti universitari e di far luce sulla dibattuta relazione tra NES e cronotipo serotino. Abbiamo, inoltre, indagato il rapporto tra NES e stagionalità. Metodi. I dati sono stati raccolti da un campione di 1136 soggetti, composto da 774 femmine e 360 maschi. Tutti i partecipanti hanno fornito informazioni demografiche e hanno compilato una batteria di questionari autosomministrati composta da: il Night Eating Questionnaire (NEQ), il Morningness Eveningness Questionnaire (MEQ), il Seasonal Pattern Assessment Questionnaire (SPAQ) e il Beck Depression Inventory (BDI). Risultati. La prevalenza della NES nella popolazione era del 5,28% (60 soggetti). I cronotipi erano così distribuiti: Mattutino: 15,3%, Intermedio 64,3%, Serotino 20,4%. Il 36,7% dei partecipanti che rispondevano ai criteri per la NES riportava bassi punteggi al MEQ, che indicano un cronotipo serotino. I dati mostrano che i punteggi ottenuti al NEQ e quelli ottenuti al MEQ sono inversamente correlati in modo significativo (r=-,22; p<,01). Il 3,6% del campione, 41 soggetti, ha soddisfatto i criteri per il disturbo affettivo stagionale (Seasonal Affective Disorder - SAD) e il 10,7%, pari a 121 soggetti, per una forma subclinica di SAD. Inoltre, l’11,7% dei soggetti con NES presentava SAD e il 5% manifestava una forma subclinica di SAD. Si osserva una significativa correlazione (r=,22; p<,01) tra la NES e la stagionalità, misurata tramite il Global Seasonality Score (GSS). Conclusioni. Il principale risultato dello studio è quello di sottolineare la forte relazione che intercorre tra NES e cronotipo serotino. I nostri dati aiutano a chiarire il dibattito presente in letteratura circa il ruolo del cronotipo serotino nell’alimentazione notturna, suggerendo che i soggetti con NES presentino un ritardo circadiano non solo nell’assunzione di cibo, ma nell’intero funzionamento. Questo studio, da quanto sappiamo, è stato il primo a esaminare la relazione tra NES e stagionalità, trovando evidenze preliminari che suggeriscono che, in accordo con studi precedenti condotti su pazienti con bulimia nervosa (BN) e BED, i sintomi dell’alimentazione notturna possono variare in modo significativo durante le stagioni. I soggetti con NES sperimentano, quindi, variazioni stagionali nell’umore e negli schemi alimentari.

PAROLE CHIAVE: sindrome da alimentazione notturna, stagionalità, disturbo affettivo stagionale, cronotipo serotino, cronotipo.

INTRODUCTION
Chronotypes are defined as the individual preference for activity and sleep during the day1. Morning type and Evening type subjects differ in sleep-wake cycle timing2-4, in the peak performance times and in the feeling after the awakening.
Several researches5-8 demonstrated an association between mood and chronotypes, especially eveningness dimension appearing to be correlated with depressive symptoms and Major Depressive Disorder (MDD)2,9. The findings of these researches are consistent with the hypothesis that evening chronotype could be considered a vulnerability factor to MDD.
Different studies investigated the relationship between personality traits and chronotypes10; evening type subjects resulted more anxious, hostile, impulsive, vulnerable and depressed. On the other hand morning chronotype was associated with traits such as conscientiousness, methodicalness and with the tendency to be compliant11-14.
Some researches highlighted the relationship between the eveningness dimension and unhealthy dietary patterns and obesity15,16. Evening type subjects have the tendency to skip breakfast more often, compared to the morning types17; and morning chronotype was more often associated with both a more flexible dietary control and a greater ability to regulate the amount of food intake, compared to the evening chronotype18. These findings suggest a correlation between the tendency to stay up late at night and the night eating behavior.
The Night Eating Syndrome (NES), first described by Stunkard19 and included in the DSM-5 category “Other Specified Feeding or Eating Disorder”, is characterized by recurrent episodes of night eating20,21 or excessive food intake after the evening meal22, morning anorexia and difficulties in sleep maintenance23. NES frequently co-occur with depressed mood that worsens in the evening20,24,25, high levels of State and Trait Anxiety26, elevated perceived stress27-29 and low self-esteem30.
The literature is not concordant about the relationship between eveningness dimension and NES. Some studies suggested that subjects with NES have a circadian delay only in their eating without affecting their global functioning22,23,31. On the other hand, Harb’s findings32 showed an association between evening chronotype and both NES and Binge Eating Disorder (BED), in a clinical population. Previous studies had already affirmed that subjects with NES had the tendency to have low scores on the MEQ, indicating an evening chronotype27,33. A recent study has also demonstrated the correlation between evening chronotype, depressive symptoms and NES in a non-clinical sample of adolescents34.
Some researches proved the effectiveness of Bright Light Therapy (BLT) in the treatment of NES, as previously reported in two case reports35,36. In a recent pilot trial37 McCune observed that BLT was effective to improve night eating behavior, mood and sleep. These findings were concordant with those achieved with Cognitive-Behavioral Therapy38 and SSRI39. The efficacy of BLT in the treatment of NES suggest the need of further systematic investigations to clear up the relationship between NES, mood and circadian rhythms.
Seasonality can be conceptualized along a continuum40,41. Kasper42,43 defined seasonality as the general tendency to experience seasonal variations in mood and behaviour, including changes in sleep length, energy level, social activity, choice of foods and appetite. Rosenthal and Wehr defined two different types of Seasonal Affective Disorder (SAD). The most recognized pattern is the winter-type, with the onset of the symptoms in fall and winter alternating with non-depressed periods in spring and summer44; whereas the summer-type is characterized by recurrent depressive episodes in the summer months followed by periods of remission in fall and winter45.
A study46 pointed out the similarities and the differences between NES and winter type SAD. These disorders have some shared features, such as consumption of high-carbohydrate and high-fat food and consequent weight gain20, circadian rhythm dysregulations20, depressive symptoms47, responsiveness to SSRI48,49 and to BLT35,36. However, NES and SAD have different patterns that indicate they are not overlapping disorders. Subjects with NES or SAD also differ in the improvement and in the worsening of mood20: the night eaters show evening mood worsening, while SAD patients often present morning worsening and evening mood improvement. Furthermore, as previously mentioned, the literature is not concordant about the relationship between NES and eveningness dimension22,23,31,32,34; on the contrary, SAD is characterized by a delayed sleep-wake cycle that affects the global functioning.
The aim of this research was to assess the prevalence of NES in a university student population and to clear up the relationship between NES, depression and chronotype. We hypothesized that evening type subjects would reach higher scores on the NEQ and on a scale to assess the severity of depressive symptoms, as other studies observed in the clinical population23, in the non-clinical population50 and in the adolescent population34. We also investigated the relation between seasonality and NES.
METHODS
Participants
The data were collected from a sample of 1136 (M=360; F=774) universitary students of the L’Aquila University, Italy. No exclusions criteria were applied.
Procedure
All subjects were invited to answer to Sociodemographic Information Form and to fill a self-report battery composed by four questionnaires: the Night Eating Questionnaire, the Morningness Eveningness Questionnaire, the Seasonal Pattern Assessment Questionnaire and the Beck Depression Inventory.
• The Night Eating Questionnaire (NEQ)51. The Italian version of the NEQ was used to assess the night eating behavior. The NEQ is composed by 15 items assessing mood, sleep difficulties, morning anorexia, food cravings, food intake after evening meal, nocturnal awakenings with ingestion of food, awareness and feelings of control during the eating episodes. The cutoff is set at 25 points.
• The Morningness Eveningness Questionnaire (MEQ)52. The Italian version of the MEQ was used to assess the chronotype; it’s composed by 19 items assessing individual differences in the timing of the sleep-wake cycle, activities and in the performance peak. The subjects, according to their total score, are divided in three different categories: Morning Type (scores 59-86), Intermediate Type (score 42-58) and Evening Type (score 16-41).
• The Seasonal Pattern Assessment Questionnaire (SPAQ), introduced by Rosenthal et al.44 is a retrospective, self-administered tool that screens for SAD and S-SAD. It is composed by four sections that investigate seasonal changes. The first section assess seasonal variations in mood, energy, sleep, social activity, weight gain and eating habits rating each item on a likert rating scale, item scales range from 0 (no change) to 4 (extremely marked change). The total scale ranges from 0 to 24, the cutoff of the self-report version of the SPAQ is set at 11 point. This score is used to calculate the Global Seasonality Score (GSS), that indicates the presence of SAD and the severity degree. A second criterion is based on the item whether seasonal changes are considered a problem, ranged from 0 (no problem) to 5 (disabling problem), a score of at least 2 indicates presence of SAD. The last session, aimed to identify the presence of SAD or S-SAD, is the one asking the subjects to indicate the months in which the symptoms occur. Kasper et al. 41 suggested that SAD subjects would indicate that symptoms get worse in December, January or February, on the other hand S-SAD subjects should feel worst in June, July or August.
• The Beck Depression Inventory (BDI)53. The scale, used to assess the severity of depressive symptoms, it is composed by 21 items, each characterized by four possible answers, scored from 0 to 3. The total score of 16 and above indicates the presence of moderate or severe depression.
• Sociodemographic Information Form. This form was developed to obtain information about participants such as age, gender, height and weight, university type, academic year. Participants were asked to provide responses to the questions appearing on the form. Body Mass Index of the participants were obtained from the answers that they provided about their height and weight. BMI was calculated using the formula BMI= weight (kg)/height²(m). A BMI below 18.5 was considered as underweight, 18.5-25 normal weight, 25-30 overweight, 30 and over obese, respectively.
Data analysis
The data analysis included descriptive statistics, chi-square test, independent samples t-test and Pearson correlation test. Descriptive statistics were used to examine the frequencies and percentages. Data are presented as mean ± SD (standard deviation) for continuous variables and percent frequency for categorical variables. The study partecipants were divided into two groups in according to NEQ cut-off. Indipendent Student’s t-test was conducted to compare NEQ total score, MEQ total score, GSS, BDI total score and BMI in two groups. Chi-square test was conducted to assess the differences in cronotype distribution (MEQ), seasonality (GSS) and the BMI categories.
Pearson correlation test (r) was computed to investigate the relationship between MEQ total score, GSS, BDI and BMI.Two-tailed p values <.05, were required for statistical significance.
All the statistical analyses were performed with IBM SPSS Statistics for Windows, Version 20.0. (IBM Corp, Armonk, NY, USA).
Ethics
This research was conducted in accordance with the Declaration of Helsinki and was approved by the Ethical Committee of the University of L’Aquila. All the procedures were carried out with the adequate understanding of the subjects, who read and signed an informed consent form before participating in this research project.
RESULTS
The sample was composed by 1136 subjects, 360 males and 774 females; the mean age was 25.97 (SD=10.78) and mean BMI of 22.38 (SD=3.6), kg/m2 (Table 1).
The 5.3% of our population (60 subjects) reached the criteria for NES.
The distribution of chronotypes in the sample was: Morning Type 15.3%, Intermediate 64.3% and Evening Type 20.4%. The 36.7% of the participants who reached the criteria for NES, obtained low scores on the MEQ (χ2=10.41 p<.005). Furthermore, the data indicated that NEQ and MEQ scores are significantly inversely correlated (r=-.22; p<.01).
The 3.6% of our population (41 subjects) reached the criteria for SAD and the 10.7% for subclinical SAD (121 subjects). Furthermore, the 11.7% of subjects with NES presented SAD and the 5% presented Subclinical SAD (χ2=13.21 p<.001). NES and Global Seasonality Score (GSS) are significantly correlated (r=.22; p<0.01).
Depressive symptoms correlate with NES (r=.43; p<.01); the 14.87% of subjects with NES had higher scores on the BDI.
No significant association between NES and BMI was seen (r=-.026, NS).



DISCUSSION
The aim of the current study was to assess the prevalence of NES in a university student population and to investigate the relationship between NES, circadian rhythms and seasonality.
The prevalence of NES in our sample was 5.28%. This estimate is similar to the one assessed by Runfola50 in university students (4%) and Nolan54 in college students (5.7%).
The main finding of this study is the strong relation between NES and eveningness dimension. According to our initial hypothesis, subjects with NES gained lower scores on the MEQ, as other researchers observed in the clinical population23, in the non-clinical population50 and in the adolescent population34. These results help to clear up the literature debate about the role of eveningness dimension in the night eating, suggesting that subjects with NES present a circadian delay, not only in the food intake, but in the entire functioning27,32-34.
We found preliminary evidence that, similarly to the findings of previous studies in subjects with BN and BED, night eating symptoms may vary significantly across the seasons; subjects with NES experience seasonal variation in their mood and in their eating patterns. Other researches have already demonstrated the association between SAD and compulsive eating behavior, especially Bulimia Nervosa (BN) and Binge Eating Disorder (BED), and suggested that sensitivity to seasonal changes in light availability was associated with risk for BED and BN 55,56. Recent findings indicated that greater seasonality scores significantly predicts binge eating symptomatology in healthy subjects57. Further investigations are needed to clarify the impact of seasonality on night eating behavior and to investigate whether the night eating symptoms get worse at northern latitudes, such as researchers observed in BN and BED55,58.
Our results did not show any correlation between NES and BMI, suggesting, in accordance to literature, that this association may be clearer in the clinical samples than in epidemiological studies50,51,54. Furthermore, other researchers59 suggested that age may be considered a mediator in the relationship between NES and BMI. Strong association between NES and BMI in subjects aged 55-60 has been found but, on the other hand, no correlation in young subjects. Our results are consistent with this hypothesis.
The findings of the current study also indicate a strong relation between NES and depressive symptoms. Further studies should investigate the role of depression in the night eating behavior.
This research has some limitations to be considered: first, the study relies on self-reported data and not clinical interview-based assessments of NES and SAD.
Furthermore, the sample is composed by students of L’Aquila University, the most originating from central Italy. This design helped to increase the homogeneity of the population, but lack to identify the differences of SAD and NES symptoms at different latitudes. It would be interesting to replicate this research at northern latitudes to investigate any variation.
Our study, as far as we are aware, is the first one to examine the relationship between NES and seasonality and to investigate the relation between NES and eveningness dimension in the Italian young adult population. The findings may have some major clinical implications and may explain the effectiveness of Bright Light Therapy in the treatment of NES.
Conflict of interests: the authors have no conflict of interests to declare.
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