I'll try not be too blinding, I've had trouble with that before.
Melatonin and prolactin are just the names of 2 hormones that are produced in your brain when you sleep. They're involved directly and indirectly in a stupid amount of processes around the body. One of the most immeadiately obvious things they do though is impact on your skeletal muscle insulin sensitivity, meaning that if you're not producing enough of them at night you're
at best making it an awful lot harder to lose bodyfat than it needs to be.
(The "at worst" is enough to make you go to bed in the middle of the afternoon -
http://www.google.co...GL_enUS203US204 )
There's a species of hamster (I think it's called a Syrian Hamster, not sure thouh), that gets studied extensively by obesity researchers. You can actually make these guys obese on demand in the lab by exposing them to different light levels. Give them summertime lighting, their sleep gets affected, you can watch their melatonin levels plummet, which causes a little metabolic cascade (involving things like their brains becoming less sensitive to leptin and prolactin production dropping off) that ends up producing insuling resistance via skyrocketing cortisol levels (the well known, catabolic "stress hormone" that bodybuilders everywhere are so terrified of). The end result of this is that they quickly turn into the rodent equivalent of those monsters that ride scooters around walmarts in order to prepare for the winter famine that their brains are signaling the imminent arrival of.
They're the most dramatic example, but the same thing can be observed to varying degrees in a bunch of different animals that evolved outside of the tropics (where they basically don't have seasons, and food availability is nearly identical all year round). Humans tend to be less amenable to sitting in cages in laboratories for months at a time while researchers expose them to different levels of light, but a lot of the same processes can be observed in sleep deprived humans (especially the increased cortisol). There's some suggestion that lack of sleep (and importantly, lack of sleep near-complete darkness) contributes towards insulin resistance in humans, which leads into the whole carbohyrdrate-craving and getting fat thing in a nasty little negative feedback loop.
Light levels at night are the primarily what controls melatonin production, and the idea of sleeping in total darkness comes from studies conducted in sleep clinics where researchers found that a little fibre optic cable shining some stupidly small amount of light on the backs of the subjects knees was enough to reduce their melatonin levels. Every skin cell seems to be able to act as a tiny little photoreceptor that provides feedback to the brain about light levels, so this doesn't bode well for streetlights shining in your window at night and little lights on alarm clocks pointed towards you, if you start getting interested in higher quality sleep.
If I remember correctly, it takes about 6 hours of continuous melatonin production at night before your brain even starts producing prolactin at all (the hormone that ties into cortisol levels), so if you're sleeping for less than that you're effectively making your training and nutritional endeavours a damn sight more difficult than they should be.
You can read more about all this in
Lights Out: Sleep, Sugar and Survival , although it gets WILDLY speculative in many places, and is annoying as hell to read at times. Some of Lyle McDonalds books have a lot more in them about the nitty-gritty of all this homormal stuff too (that's where I read about the hamsters), although oddly his solution to the problem is to take the correct drugs rather than get more sleep.
The take home message is that good sleep is at least as important as good nutrition and good training in the persuit of health and fitness. It doesn't make much sense to persue the extreme minuate of any one or two of them if the third is massively out of whack, it's what my mother would refer to as "chasing mice around the skirting boards while ignoring the bloody great elephant in the middle of the room".
If you really can't get more sleep, there's a couple of things you can do to make sure the bit you do get is at least higher quality:
-black out your bedroom (as in make it so dark you can't see your hand in front of your face)
-avoid staring at bright lights for about 2 hours before bed (this means TV and computer screens are out)
-if you really, really have to stare at screens before bed, wear some red sunglasses to filter the blue light out (blue light is the component of white light most strongly correlated with resetting melatonin production)
-take some magnesium about a half hour before (ZMA is good too). Many people find it leads to more restful sleep, and at the very least it'll probably give you inasne dreams, making being asleep more entertaining.
The smart money is on doing this stuff while also getting more sleep though.
bloody hell, longest post ever!
grole 
Chet, on Aug 22 2008, 11:53 AM, said:
But are you going to experiement with changing your sleeping habits?
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