When you eat and drink can affect sleep and how you sleep can impact how much and what you eat and drink. Meeting health-related goals like weight loss warrant attention to this interconnected relationship. Come explore the physiology so you can guide your clients thoroughly.

The body has many separate parts but ultimately (and ideally) works as a fluid system. Paying attention to the various components of human physiology helps all the parts work together fluidly; leading to more complete wellness.

How Sleep Affects Appetite

Sleep scientists have examined how a low night of sleep affects food choices by presenting study participants with a buffet of food the day after a full nights sleep and after a low night of sleep. Food choices and caloric intake are recorded to determine the effect of sleep on appetite.

Not only do study participants eat more calories after not sleeping enough, but they choose foods that are richer in carbohydrates (Walker, 2018). Appetite hormones can be measured in saliva and also blood plasma.

When a person doesn’t get enough sleep

Ghrelin increases. Ghrelin is a hormone that signals hunger. Lack of sleep causes a person to eat more than usual or necessary.

Leptin decreases. Leptin is a hormone that signals the feeling of satiation and fullness. Without sleep, satiation is suppressed and hunger overrides.

Endocannabinoids increase. Endocannabinoids do in fact cause the munchies. Enough said.

Willpower and self-control are no match for these appetite hormones. It seems the internal chemistry of the human body can be challenging to override.

Sleeping enough regulates appetite but also limits the amount of time awake for eating to occur. (Unless you are a sleepwalker and find yourself in the pantry while snoozing!)

How much sleep is enough? However much leaves a person feeling rested in the morning and able to go about her day without caffeine or other alertness supplements.

Another food-related reason to get enough sleep is “After approximately 6 hours of nonfeeding, stored glucose, or glycogen, is depleted enough to initiate a shift from glucose metabolism to fat metabolism.” (Peeke, 2018). Eating a few hours before bedtime and again shortly after waking has health benefits when there is enough sleep in between the two meals.

How Food Affects Sleep

Sleep might be better after an early and light dinner. Not just because of digestion but because the earlier a person finishes dinner, the earlier he can wind down for bed. We spend the entire day under stimulation and stress. Allowing time to relax and settle down can help a person get the sleep he needs. Dinner signals the start of evening activities.

The Better Sleep Council says, “Try to finish eating 2 to 3 hours before bedtime so your whole system is ready to relax. Drink alcohol in the early evening instead of right before bed so your body has time to digest it before you hit the sack. Make caffeine a morning-only drink and stick to other beverages in the afternoon and evening. Caffeine stays in your system longer than you might think and can disrupt your sleep.”

Some sleep and circadian rhythm experts recommend limiting carbohydrates after 3 pm and also suggest avoiding sugar in the evening. Carbohydrates are more optimally metabolized in the morning and early afternoon, based on insulin levels and sensitivity (Qian & Scheer 2016).

Protein and healthy fats might be better choices for dinner when you’re wanting to sleep well and manage weight. Hunger before bed might be best remedied with nuts as a snack.

Dr. Erin Nitschke, an ACE and NFPT Fitness Nutrition Specialist, and Precision Nutrition Level 1 Coach says, “Food is medicine. Food heals and nourishes the body and soul. When individuals choose to eat well-rounded meals daily, the body will function better overall. This includes the experience of better sleep. While there’s no “magic” diet that will cure all, nutrient-rich foods – as opposed to energy-dense foods (with the exception of nuts) will ultimately facilitate more efficient bodily processes and systemic repair.”

How Drinking Affects Sleep

Matthew Walker, a sleep scientist says that research can’t find an amount or timing for alcohol that doesn’t disrupt sleep (except daytime – which isn’t a recommendation) even though we would like it to beneficial for sleep. Research studies show that sleep is disrupted when drinking any amount of alcohol in the evening – even if the study participant felt that they slept well.

The reason caffeine is best limited to the late morning and not again later in the day is that it is an antagonist to adenosine. Adenosine is responsible for building up the pressure to sleep. The pressure starts building when you wake up. If a person feels tired mid-morning he or she might not have gotten enough sleep. If a person feels sleepy in the afternoon, suggest a walk outside, nap or mediation before reaching for caffeine.

Low sleep and caffeine consumption can become a vicious cycle, just like sleeping pills. When a supplement is used to counteract lack of sleep and in effect disrupts sleep further – it requires a person to need the supplement, even more, to get by.

Any evening beverage consumption will likely land up in a trip to the bathroom at midnight. This isn’t necessarily a problem unless getting back to sleep is challenging.

Consuming plenty of water throughout the day becomes another important beverage related habit to acquire for healthy sleep. Suggest people fill a jug of water and aim to finish it before dinnertime or set an alarm to remind them to catch up on water in the late afternoon. Sometimes the afternoon slump is simply a need for hydration, physical activity and a mental break from work.

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The human body is a complex and fascinating system made up of many working parts. When we take care of our bodies the way they were designed we don’t need as much outside support. Reaching health goals is a multidimensional process that involves attention to the many dynamic pieces.

Beyond exercise logs, help your clients keep track of habits with food journals and sleep journals. Going full circle around health habits reveals the weak links more clearly for them and you.


Walker, Matthew. 2018. Why We Sleep. New York: Scribner.

Peeke, Pamela, 2018. Is It Time to Eat Yet? Fitness Journal,15 (7).

Qian, J., & Scheer, F.A. 2016. Circadian system and glucose metabolism: Implications for physiology and disease. Trends in Endocrinology & Metabolism, 27 (5), 282–93.

Beverly Hosford

Beverly Hosford, MA teaches anatomy and body awareness using a skeleton named Andy, balloons, play-doh, ribbons, guided visualizations, and corrective exercises. She is an instructor, author, and a business coach for fitness professionals. Learn how to help your clients sleep better with in Bev’s NFPT Sleep Coach Program and dive deeper into anatomy in her NFPT Fundamentals of Anatomy Course.