It happens every year.  You finish dinner…sit down on the couch and think, “I’m just going to rest my eyes for a minute.”  Two hours later you wake up bleary eyed, and ready for round two of food.  

Most of us have experienced this Thanksgiving phenomenon and most of us, when asked, would say it was the turkey that made that post-dinner nap irresistible.  But is the turkey really the reason you pass out on the couch or is there more to the story?

The Claim: Turkey Makes You Sleepy Because Of Its Tryptophan Content

While it’s true that turkey is a great source of tryptophan and that tryptophan makes us sleepy, is turkey really to blame for the inevitable post-feast couch time?  Before we decide, lets take a closer look at tryptophan, the molecule in question.

Tryptophan is an amino acid – one of the building blocks of protein.  Some amino acids can be made by the body, but others like Tryptophan, must be consumed as part of a healthy diet.  One of the most important roles Tryptophan plays happens in the brain where it is converted into a neurotransmitter, a chemical that allows brain cells to communicate with eachother. Tryptophan is the only substance that can be converted into the neurotransmitter serotonin.   

Most of your brain cells are influenced by serotonin which regulates things like mood (think depression), sexual desire and function, appetite, sleep, memory and learning, temperature regulation, and some social behavior.  In terms of our body, serotonin can also affect the functioning of our cardiovascular system, muscles, and various elements in the endocrine system.

Tryptophan, by way of serotonin, also plays another role.  Serotonin made from tryptophan is converted to melatonin – the essential hormone in regulating wake/sleep patterns.

Clearly tryptophan plays an instrumental role in balancing mood and sleep patterns, but turkey isn’t even a food that contains the most tryptophan.  Foods like chicken, tuna, mushrooms, scallops, shrimp and soybeans contain just as much tryptophan or more tryptophan than turkey and, we don’t need to take a nap every time we eat those foods.  What gives?

As it turns out the whole meal works as a macronutrient symphony to sing us to sleep.  When we load up our plate with foods like mashed potatoes, sweet potatoes and stuffing we introduce a large load of simple carbohydrates to our bodies.  Because of a rapid rise in blood sugar, the body signals the pancreas to release insulin.  Insulin, in addition to decreasing blood sugar, also reduces the amount of amino acids circulating in the blood.  All amino acids except tryptophan which now has a direct line to the brain.  Large amounts of tryptophan cross the blood brain barrier where it stimulates serotonin production and creates feelings of relaxation and sleepiness.

Case closed?  Not quite…

When we eat an exceptionally large meal the body diverts blood from other areas of the body to the stomach in order to aid digestion, making us feel lethargic.  Not to mention the sedative effect of any alcohol you consume with dinner.

And, of course, we must consider the environment.  The holidays can be a stressful time.  Putting on the meal is often a production and having family and friends around creates more social interactions than usual.  After the meal, there is usually a sense of relief and people look forward to sitting back and relaxing for a while.

So, is the turkey to blame?  Without an abundance of carbohydrates, tryptophan would not be able to move so easily into the brain.  Add in the typical holiday environment and who can be blamed for the urge to duck cleanup duties and take a nap!

Status: Myth BUSTED

So, what can you do to prevent that post Thanksgiving meal lethargy?

1. Get a good night’s sleep the night before.  Sleep is essential in appetite regulation.
2. Eat a protein rich breakfast.  This will prevent you for overeating later in the day.
3. Exercise in the morning.  Remember those Thanksgiving Day Races?
4. Don’t use the holidays as an excuse to overeat, but rather to enjoy visiting with friends and family.
5. At dinner load your plate up with turkey, a good source of lean protein, as well as fresh fruits and fresh vegetables.
6. Go for a walk after dinner instead of moving to the couch.  Walking will improve digestion as well as prevent you from feeling tired.

If you still feel like you need a nap after dinner, go ahead – take one and enjoy it; Thanksgiving only comes once a year.