Introduction

Did you know that up to one in four people with obesity may struggle with night eating? Night Eating Syndrome (NES) is more than just a late-night snack. It’s a pattern of disordered eating linked to sleep problems, emotional distress, and health risks like obesity and depression.¹ 

While many people believe that NES is caused by habits or stress, evidence suggests that your genes may also play a role. So, can NES be passed down through families? This article explores the genetic side of NES. We’ll look at research on family history, clock genes, and what that means for diagnosis and treatment. By the end, you’ll have a better understanding of how genetics may influence NES, and what steps you can take if it runs in your family.

Answering the main question

Yes, NES may be hereditary. Research shows that NES tends to run in families. A study found that people with NES were nearly five times more likely to have a family member with similar symptoms.² Other research has pointed to mutations or disruptions in genes that control the body’s internal clock, like PER1 and PER2.³ These genes regulate circadian rhythm, the cycle that tells your body when to eat and sleep. If this rhythm is off, it may cause someone to feel hungry at night instead of during the day. While NES is not purely genetic, your family history and DNA may increase your risk of developing it.

Read on

This is just one piece of the puzzle. NES is a complex disorder influenced by genetics, sleep, mood, and environment. The sections below break down how genetics may be involved and what that means for your health.

What is Night Eating Syndrome (NES)?

NES is a type of eating disorder. It was first described in 1955 by Dr. Albert Stunkard, who noticed a pattern in people who were obese: they skipped breakfast, ate a lot in the evening, and sometimes woke up to eat at night.⁴ Over time, NES was recognised as a distinct disorder with specific features.

To be diagnosed with NES, a person must:⁵

• Consume at least 25% of daily calories after dinner
• Wake up to eat at least twice per week
• Have these symptoms for at least 3 months
• Experience distress or impairment from the behaviour

Unlike binge eating disorder, NES is marked by frequent, smaller meals rather than large episodes of overeating. It’s often linked to sleep disturbances, depression, and anxiety. People with NES may feel shame, frustration, or a loss of control over their eating patterns.⁵

Family patterns in NES

One of the clearest signs that NES may have a genetic basis is that it runs in families. In a study by Lundgren et al., people with NES were 4.7 times more likely to report family members with similar eating behaviours compared to people without the disorder.² This suggests there may be inherited traits that contribute to NES.

Another paper reported a case of three generations in the same family experiencing NES symptoms.⁶ These reports suggest a biological component beyond just learned behaviour. However, it’s also possible that shared environments, like household routines or cultural attitudes toward food, play a role.

Twin studies are often used to separate the effects of genetics and environment, but there are few twin-specific studies on NES. But, similar studies on related disorders, like obesity and insomnia, show a strong genetic influence, which may extend to NES.⁷

Circadian rhythm and the role of clock genes

Circadian rhythm is the body’s internal clock. It tells you when to wake, eat, and sleep. This rhythm is controlled by a group of genes, often called “clock genes”, including PER1, PER2, CLOCK, and BMAL1. These genes work together to keep your body in sync with the day-night cycle; disruptions in these genes can throw off your schedule.³

In humans, changes in PER1 and PER2 have been linked to delayed sleep phase disorder, where people fall asleep and wake up much later than usual. These same genes may also affect hunger signals, leading to more eating at night.⁸

Another gene of interest is MC4R, which regulates appetite. Variants of this gene are known to be associated with obesity and have been identified more frequently in individuals with NES, although the evidence is still emerging.⁹

Stress, mood, and gene interactions

NES is often associated with mood disorders. Depression, anxiety, and post-traumatic stress disorder (PTSD) are common in people with NES.¹⁰ This overlap may not be a coincidence. Some genes linked to mood regulation, like 5-HTTLPR, which affects serotonin transport, may also play a role in eating behaviour.¹¹

Serotonin helps regulate mood, appetite, and sleep. Disruptions in serotonin pathways may explain why some people with NES feel driven to eat at night, especially during times of stress or sadness. Studies have found that people with NES often have lower levels of serotonin or its metabolites.¹¹

This doesn’t mean genes alone cause NES. Instead, genes may make someone more sensitive to stress or more likely to develop NES when combined with poor sleep or emotional triggers.

Environmental factors still matter

While genetics may set the stage, the environment often pulls the trigger. Poor sleep, inconsistent eating patterns, and high stress can all contribute to NES. People who work night shifts or live in chaotic households are at higher risk.⁵ 

Childhood experiences may also play a role. Trauma, neglect, or early life stress can alter how the brain regulates hunger and sleep, increasing the risk for NES later in life.¹² 

So even if NES has a genetic component, that doesn’t mean it’s unavoidable. Lifestyle and therapy can make a big difference.

Expanding the genetic landscape of NES

While PER1, PER2, and MC4R are the most researched genes related to NES, new data points to additional genes involved in both metabolic regulation and sleep-wake cycles. Genes like CRY1 (cryptochrome circadian regulator 1) and NPY (neuropeptide Y) are being studied for their impact on hunger and alertness. CRY1, for example, works closely with PER genes to maintain circadian rhythm. Variants in CRY1 have been associated with delayed sleep and increased nighttime activity, which can easily spill over into late-night eating behaviour.¹³

In addition, leptin and ghrelin, two hormones that control hunger and satiety, are regulated by genes that can differ between individuals. NES patients often show lower nighttime leptin (which tells you to stop eating) and higher ghrelin (which signals hunger) levels compared to others. This imbalance may be genetically driven in some people, further supporting the hereditary theory.^10,11

Emerging genetic studies and tools

As genetic research tools become more advanced, scientists can now scan entire genomes for patterns. Genome-wide association studies (GWAS) are helping identify clusters of genes that might be linked to NES. While this research is still early, it’s already uncovered multiple genetic “hotspots” that seem more common in people with disordered eating at night.¹⁴

This kind of work is crucial. It may lead to a future where we can screen people based on genetic risk. It could also allow for personalised treatments. For example, someone with disrupted PER2 activity might benefit more from early-morning light therapy, while someone with NPY dysregulation might need medication to reduce nighttime hunger signals.¹⁴

Summary

If NES has a genetic component, recognising it can help with early intervention. Doctors could ask about family history during assessments and flag people at higher risk. If clock gene mutations are involved, treatments like light therapy, which reset circadian rhythms, might work better for some patients.

In the future, we may even see genetic tests that help guide treatment. But even now, just knowing that NES runs in families can help people feel less shame. It shows that NES is not a weakness or choice; it's a medical issue with real biological roots.