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Nighttime Eating, Sleep-Wake Cycles, and Stress Management

Dr. Linda J. Dobberstein, DC, Board Certified in Clinical Nutrition

The New Year naturally brings resolutions to make healthier habits. With busy and erratic schedules, regular mealtimes often fall by the wayside. Meals are skipped or other irregular eating patterns occur. In addition, inconsistent sleep-wake routines, changing work shifts, taking care of young children or elderly parents at night, or simply getting into a bad habit of staying up too late at night, contributes to altered circadian rhythms. These irregular patterns can increase nighttime eating and it comes with a substantial cost to your metabolism. Get your nighttime eating under control to help your New Year’s goals and healthier you!

Night Eating Syndrome

Night Eating Syndrome is the term applied to individuals who consume more than 25 percent of their daily nutrition after the evening meal two or more times per week. In addition to the late night eating pattern, individuals who follow this pattern also have poor quality sleep and no appetite in the morning.

The pattern of eating late at night causes obvious challenges to metabolism. Research shows that individuals who eat significant amounts of food after dinner were “significantly and independently associated with increased body mass index (BMI), shorter sleep duration, later sleep-wake schedule, and higher insomnia scores”. In other words, eating a big snack or meal before bed was linked with weight gain/obesity, insomnia, poor quality sleep, and disrupted body rhythms.

Night Eating Syndrome was first described in 1955, but little attention was given to it until the late 1990’s. It is mostly attributed to a delay in the circadian rhythm of eating along with other factors like high levels of the hormone prolactin relative to other hormones. Night Eating Syndrome is not the same as Sleep Related Eating Disorder in which you can’t recall getting up in the middle of the night to raid the refrigerator.

Metabolic Effects of Night Eating: Prolactin

The hormone prolactin was originally discovered and named for its role in promoting lactation. It has since been found to be involved with numerous actions throughout many internal organs and the nervous system. Further research has found that prolactin is significantly involved with body weight management, adipose tissue, pancreas, adrenal glands, and other tissues in response to stress and much more.

Things that Impact Prolactin

Studies show that secretion of prolactin in the brain and elsewhere in the body is greatly impacted by light. Animals that were either in a state of constant light or light deprivation, i.e. disrupted day-night/light-dark rhythms experienced higher prolactin levels. Several other stressors, including academic stress, have been found to stimulate production of prolactin. Increased levels of prolactin have also been found with low thyroid function.

Neurotransmitters, dopamine, GABA, and histamine affect prolactin levels too. Dopamine and GABA are instrumental in dampening prolactin secretion and activity in the brain. However, increased histamine levels contribute to prolactin secretion.

Research on prolactin is complicated. Much is left to be learned about its complete role in metabolism, weight management, and nighttime eating. We do know that dysregulation of the circadian rhythms and metabolism linked with nighttime eating and the hormone leptin are problematic. Theoretically, it is likely that prolactin is linked with leptin somehow, but research is inadequate to prove this. Here are some practical take away points to get your new year started on the right track and stop the midnight food raids.

Practical Points 1. Circadian Rhythms.