In part one of this series, we discussed a relationship between sleep and weight, and three hormones that had serious implications when it comes to weight loss or gain. Two hormones were discussed in part one of this series (leptin and cortisol) and today we are going to discuss the third, human growth hormone (HGH).

A 1999 study published in "The Lancet" followed a group of young men who were limited to just 4 hours of sleep for sixteen straight days had increased levels of cortisol - which slows metabolism and causes fat to be stored - and decreased levels of leptin - which cause a "satisfied" feeling when the body has consumed enough food.

As a follow up to this study, Eve Van Cauter (the head researcher) looked more deeply into the effects of sleep deprivation on the body's chemistry - particularly as it pertains to weight loss or gain. The results of the follow up study were published in the Journal of the American Medical Association in 2000.

The follow up study looked at the phases of sleep that a person experiences and how those phases change as a person gets older. It seems that as men age, they experience less "deep sleep" than when they were younger. Women, on the other hand, experience about the same amount of "deep sleep" throughout their lives, until after menopause when their sleep patterns more closely match that of a similarly aged male.

So what, you ask, does that have to do with weight gain or loss? The answer varies whether you are a male or a female, and has to do with the third hormone we will discuss: human growth hormone. HGH, as it is commonly called, is secreted into the blood stream for the purpose of repairing muscle and tissue. If you are exercising, you are actually damaging your muscles by creating tiny tears in the tissues. This is how we gain lean muscle. We break down the muscle when we exercise, and then we rebuild it at night while we sleep.

Men secrete two-thirds of their HGH during the periods of "deep sleep" and women secrete one-third of thiers. If you are robbing yourself of valuable sleep, you aren't getting to the point where HGH is getting into your blood stream. The less "deep sleep" that a person experiences, the less HGH that is available to build lean muscle.

What makes this worse is that the study found (at least for men) that even if they get the same number of hours of sleep as a younger man, they still get less "deep sleep" than their younger counterparts. Van Cauter's research showed that a 45-year-old man's HGH production will have decreased by 75% as compared to a 25-year-old.

Since the odds are stacked against us as we get older, what are we to do? As you may be aware, the body is an efficient and hard-working machine. It has three major processes that operate over the course of the day. We work (exercise), we make energy (digest) and we repair (sleep), just not all at once. Each of the processes requires too much energy to be efficiently performed while another is being completed. If you don't believe me, eat a big meal and go run for two hours.

The body was designed to fuel and then work and then refuel and work some more, and then repair itself overnight. The more HGH that is released into the blood stream, the more muscle repair, and even lean muscle gain, takes place. Two things that we can do to help stack the odds in our favor are to make time for exercise and sleep, and to supplement with time release whey protein before sleep.

Supplementing with whey protein (such as NightTrainer, http://www.nighttrainer.com) puts the building blocks of muscle (protein and amino acids) into your body so that they're available to help the HGH build more lean muscle. (An added benefit I've noticed is that because it comes in chocolate and vanilla flavor, I can avoid eating dessert when I'm craving something sweet late at night, knowing I'll soon be enjoying my protein drink.)

As has been chronicled here and myriad other texts, building lean muscle is exactly what one needs to do in order to win the battle of the bulge. Sweet dreams!