Falling asleep naturally Part 3: Tryptophan and Insulin

So far we've established that we get the essential amino acid, tryptophan from foods, that it is converted by B6 and manganese (and sunlight) to the "feel good" neurotransmitter serotonin, which is converted by more B6 and manganese (and dark) to the sleep-inducing melatonin (I'll talk more about melatonin soon, I promise).

Unfortunately for the serotonin using nerves, tryptophan must share its "transport bus" with 5 other amino acids; tyrosine, phenylalanine, valine, leucine and isoleucine.

Consequently, tryptophan is typically out-numbered about 8:1 (remember, there are 8 essential amino acids) in its competition to secure its transport through the blood brain barrier into the brain.

Tryptophan's effects on carbohydrates and obesity

Eating a high protein diet to provide more tryptophan only worsens the problem by correspondingly increasing the intake of the 5 competing amino acids. Ironically, the only dietary strategy that increases brain tryptophan supply is to eat a high carbohydrate diet.

To understand how tryptophan and carbohydrates work together to relax you, picture the various amino acids from protein foods as passengers on a bus. A busload containing tryptophan and the other amino acids arrives at the brain cells. If more non-tryptophan "passengers" get off the bus and enter the brain cells, neuroactivity will rev up. If more tryptophan amino acids get off the bus, the brain will calm down.

When large amounts of carbohydrates are eaten, blood glucose levels increase rapidly. Once the body detects these elevated blood glucose levels it releases the hormone insulin to lower the resulting high blood sugar. The insulin also clears from the blood most of the 5 amino acids that compete with tryptophan for a ride to the brain. Tryptophan then has the "bus" all to itself, allowing more tryptophan to reach the brain.

As the blood glucose levels peak and then fall off, insulin does the same, however insulin levels peak later than blood glucose. Once blood glucose levels reach normal again, it takes insulin a little bit longer to reach normal itself. It is this lag time in normalization of insulin levels which gives us those sugar cravings after carbohydrate rich meals. This is because blood sugar levels are normal but we still have insulin present in the blood and that insulin needs something to do; so it has the effect of asking the body for more sugar. That's why we get hungry even though we just ate a few hours ago.

This cycle is instinctively known and practiced by many people who eat large amounts of carbohydrates like bread, cakes, pies, ice cream, chips, pizza, candy etc., especially when they are feeling depressed, stressed or anxious.

The increased brain serotonin this produces lowers arousal and anxiety, promoting a (temporary) sense of well being and security. However, this strategy comes at a price, the same insulin which enhances brain serotonin also enhances the conversion of the fats, carbohydrates, and amino acids cleared from the blood into stored body fat!

High insulin levels prevent your body from using this fat as an energy source, so it simply begins to accumulate. Eventually, if insulin levels remain continuously high, your cells will become insulin resistant, meaning that they will stop accepting any more glucose at all. In effect, they shut down, and stop caring about how much sugar is in your blood. What happens next is that the amount of glucose in the blood stream becomes unregulated, and things get bad in terms of blood glucose toxicity and insulin damage, which results in diabetes, heart attacks, blindness, the need for limb amputation and other disasters.

However, this is just focusing on the glucose levels in the system. Having consistently high insulin levels is even worse. Insulin is pro-inflammatory, and is now believed to cause atherosclerosis, the stiffening of artery walls, the rise in blood pressure, the blockage of your circulatory system--and you get the picture.

So what we want is enough protein to provide tryptophan, enough carbohydrates to cause insulin to "bind up" the energizing amino acids but not so much as to cause a rapid spike in blood sugar with its resulting spike in insulin.

What's a person supposed to do?

Next: Complex vs Simple Carbohydrates

The Insomnia Series
Falling asleep naturally Part 1
Falling asleep naturally Part 2: The Interaction of Biochemicals