Introduction 

Night eating syndrome (NES) is an eating disorder characterised by consuming the majority of daily food at nighttime, difficulty sleeping, and a lack of appetite in the morning. It affects both physical and mental health, and it has been increasingly linked to disruptions in the body’s natural circadian rhythm, the internal clock regulating sleep, metabolism, and appetite.
Several things contribute to the development or worsening of this syndrome, one of which is exposure to artificial light, particularly blue light emitted by screens and LED lighting, which is often unavoidable after sunset. This exposure suppresses the secretion of the sleep hormone called melatonin, which can also throw off hormonal and metabolic processes that influence when and how much we eat.

In this article, we will explore this relationship in depth, analysing the how and why.

Understanding night eating syndrome

NES is more than a behavioural pattern; it is often an underdiagnosed condition that blends elements of disrupted sleep, irregular eating patterns, and emotional distress. First described in the 1950s and now recognised by both the DSM-5 and the International Classification of Sleep Disorders (ICSD-3), NES is characterised by a delayed pattern of food intake, with individuals consuming a significant portion of their daily calories in the evening or during nighttime awakenings.¹

Some of the key symptoms found are: 

• Evening Hyperphagia: Consuming more than 25% of total daily food intake after the evening meal
• Night Ingestions: Waking up during the night to eat, often accompanied by a sense of compulsion
• Morning Anorexia: Lack of appetite or skipping breakfast
• Sleep Disturbances: Difficulty falling asleep or staying asleep, often related to food cravings
• Mood Disturbance: Increased stress, anxiety, or depression in the evening or night

The syndrome carries serious implications, and it has been associated with increased risks of weight gain, obesity, insulin resistance, and poor blood sugar regulation, as well as heightened feelings of guilt, low self-esteem, and psychological stress.²

The role of light in circadian regulation

Our bodies possess an internal 24-hour clock called the circadian rhythm, which regulates many vital processes, including our sleep, awakening, and even hunger. At the centre of this system, there is a part of the brain called the Suprachiasmatic Nucleus (SCN) that works by sending signals to help coordinate all the rhythms in our body; it functions as the "master clock.

One of the powerful signals that keeps our internal clock in sync is light, so when our eyes detect light, especially in the morning, it tells the SCN that it’s time to be awake and alert. In contrast, darkness signals the body to start winding down and preparing for sleep.

This process is closely tied to a hormone called melatonin, which is produced by the brain,  more specifically by the pineal gland, in response to darkness and plays a key role in helping us relax and fall asleep. Light helps set our daily rhythms, and too much artificial light at the wrong time can confuse the body’s natural signals, affecting not just sleep, but also when we feel hungry or full.

Blue light and melatonin suppression

One of the biggest disruptors of this natural rhythm is blue light. This is a type of light that comes from screens, like phones, tablets, TVs, and LED lights. While blue light during the daytime helps us stay focused and alert, too much of it in the evening can send the wrong signals to our brain.

At night, our bodies are supposed to make melatonin, which helps us fall asleep. But when we’re exposed to blue light after sunset, it can block its production, and this will affect 09othe onset of sleep as well as the quality and the quantity.⁴

The biological link between light and night eating syndrome

When looking at conditions like Night Eating Syndrome (NES), the connection between light exposure, melatonin, and the body’s internal clock becomes especially important.
At night, looking at screens like phones and TVs can stop the body from making melatonin, the hormone that helps us feel sleepy. When melatonin is low, it’s not just harder to sleep—your body also starts making more of the hunger hormone called Ghrelin, which makes you feel hungrier.

This mix-up in signals can throw off your body’s natural rhythm and lead to:

• Sleeping later than usual and struggling to fall asleep
• Waking up in the middle of the night and feeling the need to eat
• Eating more at night because your appetite is harder to control

Studies show that people with night eating syndrome often have lower or delayed melatonin levels at night, which could be one reason for their symptoms. Understanding this connection helps us take the right approach when dealing with it. 

Emotional and hormonal consequences of light disturbance in night eating syndrome

Although melatonin is crucial in the sleep-wake cycle, it is not the only hormone influenced by disturbed sleep and nighttime illumination. Many other important hormones are implicated in Night Eating Syndrome (NES), and their imbalance might help to explain the psychological as well as physical difficulties related to the disorder.

Commonly referred to as the "hunger hormone," Ghrelin is among the most crucial hormones in this mix. Natural rises in Ghrelin before meals signal the brain when it's time to eat. But when artificial light at night suppresses melatonin production, Ghrelin release might rise abnormally, especially during hours when the body is supposed to be asleep. This nighttime increase in hunger can drive the obsessive eating habits observed in NES and make it more difficult to resist urges. 

Conversely, those who suffer from sleep deprivation or circadian misalignment often have less Leptin, the hormone in charge of signalling fullness and controlling energy balance. A combination of high Ghrelin and low leptin can lead to nocturnal overeating and poor impulse control around food, especially in individuals who are already prone to disordered eating patterns.

Still, the hormonal effect goes beyond appetite. Moreover, insulin sensitivity is influenced by circadian rhythms. Exposure to strong light late in the day might cause the body to lose sensitivity to insulin, which is the hormone that controls blood sugar. Those who suffer from irregular eating patterns and disturbed sleep typically find it more difficult to control their glucose. This can, over time, lead to weight gain, insulin resistance, and a higher risk of type 2 diabetes or prediabetes. These hazards are more noticeable among shift workers and those with irregular daily schedules, groups that are also more prone to have NES.

No less important is the impact of light and sleep disturbances on mental health. Many times, NES is associated with sadness, anxiety, and persistent stress. Bad sleep quality can aggravate emotional states and set off a vicious cycle whereby emotional discomfort causes night snacking, which compromises sleep even more and results in more severe mood instability. Furthermore, interference with altered circadian rhythms could include the brain's generation and control of serotonin, a neurotransmitter vital for mood, emotional stability, and hunger control. For those with NES, poor mood or hopelessness may be caused in part by decreased serotonin activity, especially in the evening.

Studies published in the Journal of Biological Rhythms and the International Journal of Endocrinology confirm this link by demonstrating that those who spend more time in artificial light at night are more prone to suffer from both metabolic malfunction and emotional dysregulation.

These results highlight how important better light hygiene, the way we control light exposure, may be in not only controlling sleep and eating patterns but also in enhancing mental health results. Combining emotional support, hormone balance strategies, and light management techniques may give those with night eating syndrome more complete and long-lasting relief than concentrating on one element alone.⁵

Practical tips to sleep better and reduce nighttime eating

Knowing one of this syndrome's potential worsening or inducing factors is key to managing it. And for light exposure, there are several ways we can take to support your body’s natural rhythm and consequently help improve both sleep and appetite control. Here are some helpful lifestyle tips:

Limiting screen time 1–2 hours before bed

Turning off phones, computers, and TVs at least an hour or two before sleeping, since the blue light from these devices can trick your brain into thinking it’s still daytime and stop your body from producing melatonin, the hormone that helps you fall asleep.

Use blue-light blocking glasses or night mode

If using screens at night is necessary, wearing blue-light-blocking glasses or turning on the “night shift” or “night mode” setting on your devices can help reduce the amount of blue light, and they are gentler on your eyes and brain.

Creating a sleep-friendly environment

A calm environment supports deeper, more restorative sleep. Keeping your bedroom dark, quiet, and free from screens. Using blackout curtains, turning off bright lights, and avoiding late-night media. 

Sticking to a regular schedule

A consistent routine helps keep your internal clock in sync and can reduce nighttime hunger cues. Trying to go to bed and wake up at the same time every day, even on weekends. Helps you regulate your internal clock and supports better sleep and a better lifestyle.

Using melatonin wisely

Melatonin supplements may help in some cases, but they’re not for everyone. Always speak with a healthcare provider before starting melatonin to make sure it’s safe and appropriate for you.

Summary

Night Eating Syndrome (NES) is closely linked to disruptions in the body’s natural circadian rhythm. Exposure to artificial and blue light at night—especially from screens—can reduce melatonin levels, delay sleep, and affect appetite hormones. These changes may lead to increased nighttime awakenings and food cravings. Research suggests that managing light exposure in the evening may help regulate sleep and reduce symptoms of NES.

Conclusion

By recognising the role of light in our sleep and eating patterns, we can take simple yet powerful steps to support our health. Limiting evening screen use, improving sleep hygiene, and protecting melatonin production may help restore balance for those struggling with NES. A well-regulated circadian rhythm is key not only to better sleep but also to healthier eating habits and overall well-being.