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By Madelyn Fernstrom, PhD

If you’re having trouble getting enough zzz’s, many will be quick to suggest having a glass of wine, a cup of warm milk or a banana. But do certain foods really boost sleep? It’s the $64,000 question.

No one more than me would like there to be a simple, direct connection between food and sleep. In my former, active life as a neuroscientist, this was a main area of my research.

And while there are bits and pieces of truth to many of the food-sleep connections, most are based on the cherry-picking of scientific evidence.

Sleep is complex and involves many biological and behavioral systems. So let’s separate fact from fiction:

Fact #1: Caffeine interrupts sleep

Skip caffeinated beverages from 3 p.m. on (noon if you’re caffeine sensitive). This means coffee, tea, soda and energy drinks. Caffeine is broken down slowly in your body, so you need to allow adequate time to lose the stimulant effects. Stick with decaf, herbal teas and caffeine-free soda.

And while red wine (or any other alcoholic beverage) may provide immediate relaxation benefits, alcohol is a well-studied sleep disruptor.

Fact #2: Chocolate can have negative affects on sleep

Cut out the evening chocolate or hot cocoa, especially if you’re caffeine sensitive. While chocolate contains almost no caffeine, it does contain higher amounts of a caffeine-like compound called theobromine, which may keep you awake.

Fact #3: A high-fat meal before bed can be disruptive

Avoid a large, high-fat meal for at least three hours before laying down in bed. Fat slows the emptying of food from your stomach, and a full stomach interferes with both falling and staying asleep.

Have a small low-fat snack (up to around 150 calories) within an hour of bedtime if you choose – especially if you have an early dinner and go to bed late (more than four hours from dinner to bedtime). For some people, going to bed on an “empty” stomach is unsettling and interrupts a comfortable drifting off to dreamland. Try a small piece of fruit, a cup of low-sugar cereal, a few cups of air-popped popcorn, or a small container of plain Greek yogurt.

And now, here are some popular myths, which sound too good to be true (and they are).

Myth #1: Turkey can send you quickly into dreamland

Many people believe protein foods (especially turkey) can help you sleep because they contain the amino acid tryptophan; and tryptophan is converted into serotonin, the brain chemical connected to sleep. More tryptophan, more serotonin, more sleep, right?

It’s not exactly the case, when we look at how the body handles tryptophan in food. While protein foods do contain tryptophan, they are also rich in other amino acids that compete with tryptophan for uptake into the brain (where it needs to be converted to serotonin to impact sleep or other behaviors). But there are loads more of the other amino acids, in addition to tryptophan, all trying to get into the brain through the same entry. So, protein foods, while containing tryptophan, are not helpful in raising brain serotonin. And as hilarious as the “Seinfeld” episode where a woman famously falls asleep after eating turkey (it’s the serotonin factor!), it’s not true. This covers the warm milk explanation as well. While warm milk is often associated with sleepiness, it’s likely due to the sense of warmth and relaxation, but not a serotonin effect on the brain.

Myth #2: A banana can help you get some zzz’s

Some may suggest eating bananas because they contain serotonin. While bananas do contain serotonin, that serotonin doesn’t pass into the brain, and so has no impact on boosting the brain serotonin that can ultimately effect sleep.

Myth #3: Carbo-loading is great for sleep

You’ve probably also heard of some people eating carbohydrates because they promote serotonin production in the brain. This is also true, but under very limited conditions. The meal must be nearly 100 percent carbohydrate. It also takes at least a couple of hours for the metabolic impact of pure carbohydrates to impact serotonin levels in the brain. Why carbohydrates? Because surprisingly, eating pure carbs (remember, no protein) also stimulates insulin secretion – which boosts tryptophan entry into the brain by causing all of those other amino acids competing to brain entry to decline, and go into muscle instead. That gives tryptophan the competitive advantage to enter the brain easily – to be converted to serotonin.

But like bananas and proteins, much of the claimed carbohydrate impact IS related to the belief that these foods will promote sleep. But when it comes to foods and sleep – if you find something is helping, then it’s a good solution for you. Just beware that with so many other claims, if it sounds too good to be true, it probably is.

Your best bet for a better night’s sleep is to focus on an overall healthy lifestyle (stable weight, physical activity, stress management), and good sleep hygiene (cool, dark, quiet). It’s long-term healthy habits that will have the greatest impact on your sleep.

And if you’ve tried all of this, and still struggling, pay a visit to your doctor, or a mental health professional for further medical and/or behavioral management.

Madelyn Fernstrom, Ph.D. is the NBC News Health Editor. Follow her on Twitter @drfernstrom.