The link between circadian rhythm and night eating syndrome

By Neha MathurJan 9 2024Reviewed by Lily Ramsey, LLM

In a recent study published in Nutrients, researchers assessed night eating syndrome (NES) symptomatology in Greek-origin people and its possible links with circadian rhythm. 

The study concentrated on three different chronotypes: morning, intermediate, and evening. People with a morning chronotype typically favor early to bed and early to rise routines, in contrast to evening types who perform best later in the day.

Gaining a better understanding of Night Eating Syndrome (NES) symptoms can aid in creating tailored chronotherapy treatments. These treatments aim to alleviate NES symptoms, thereby reducing their negative impact on overall health.

Study: Beat the Clock: Assessment of Night Eating Syndrome and Circadian Rhythm in a Sample of Greek Adults. Image Credit: Stock-Asso/Shutterstock.com

Background

Night eating syndrome (NES) is a type of Other-Specified Feeding or Eating Disorder (OSFED) characterized by excessive food intake during the evening and night hours at a frequency of at least twice a week. 

People with this condition are commonly obese or overweight, sleep poorly, and remain in depressed mood. They also have an urge to eat upon nocturnal awakenings.

Studies have established a link between the circadian (circa “about” and diem “day”) system and energy metabolism, with the suprachiasmatic nucleus (SCN) playing the central role in this phenomenon. It regulates sleep-wake cycles, hormone release, and body temperature to synchronize the circadian clock to the external environment.

Any disruption to circadian rhythm referred to as chronodisruption, manifests as metabolic disturbances, such as increased blood pressure, obesity, and elevated fasting blood sugar.

Its misalignment with inadequate sleep can also affect brain function, further exacerbating metabolic disorders and sleep disturbances.

About the study

For the present study, researchers used a limited sample of 533 adults from Greece and Cyprus to examine NES symptomatology and its association with chronotype.

They recruited people online through social media, and the data collection process began in May 2021 and continued till July 2021. After each participant provided their informed consent for survey participation, the team collected data from them and kept it anonymous. 

All participants recruited in this study completed the Night Eating Questionnaire (NEQ) comprising 14 questions, with each contributing to the total NEQ score, spanning between zero and 52.

A NEQ score exceeding 25 points indicated confirmed NES, while a score of ≥30 had high specificity.

Overall, NEQ helped assess the psychometric properties and severity of NES, but positive screening did not always coincide with NES diagnosis.

The team used another questionnaire called Sleep, Circadian Rhythms, and Mood (SCRAM) to assess each participant’s circadian rhythm, sleep quality, and mood. 

Participants self-reported their body weight and stature, which helped the team compute their body mass index (BMI); BMI ≥ 25 kg/m² and < 30 kg/m² indicated overweight, and BMI ≥ 30 kg/m² indicated simple obesity.

The team used independent samples t-tests to determine gender-associated variations between continuous variables, a chi-square test to explore differences between categorical values, and logistic regression models to explore the relationship between the NEQ and the SCRAM questionnaire in total and sub-scales. 

Finally, they used Cronbach α to assess the internal reliability of the instruments used, with values >0.6 and >0.8 indicating an acceptable level of reliability and a good fit, respectively.

Results

The authors noted a trend towards higher NES-positive screening among overweight and obese people compared to those with normal body weight, even though the total NEQ and SCRAM raw scores in different BMI categories were comparable.

Accordingly, the observed prevalence of NES was relatively high, with 17.8% (NEQ threshold ≥ 25) and 8.1% of the participants (NEQ threshold ≥ 30) diagnosed with NES.

The mean NEQ for the sample was 18.0 ± 7.4, with no differences observed between sexes. In sub-analyses, there was no association between NES and BMI and NES and sex of the participants.

When using the NEQ threshold ≥ 30, NES incidence was positively associated with the morning chronotype; however, the average total SCRAM score of the sample was moderate, indicating most participants had the intermediate chronotype. 

Additionally, there was a negative association of SCRAM with “Good Sleep”, and each point increment in the depression score increased the odds of NES by 6%. Thus, depression appears to largely affect NES symptomatology. 

Conclusions

The study sample size did not allow for generalizations, so more research is required to understand whether observed elevated NES symptomatology in this study was limited to the Greek population at a single time point. 

Furthermore, the finding that NES was associated with the morning chronotype may be an artifact due to the relatively low internal validity of the SCRAM questionnaire.

Thus, further research is warranted to test the tool in more generalizable samples and determine its test–retest reliability and predictive and discriminant validity.

Overall, NES remains an independent clinical entity requiring further investigation for its pathophysiology and management.