The Science of Sleep

It's an experiment everyone conducts at least once. Whether you have a deadline to meet, an exam to prepare for, a conversation that just doesn't end or a brain that won't quit, at some point everyone tests her ability to stay awake for extended periods. For me, it was my sophomore year in college, when I once stayed awake for something like 33 hours. I remember the rush of adrenaline that got me through the night, the dry eyes, the semi-achy head, the painful stab of the bright morning sun the next day and the fog of exhaustion. By late that afternoon I was succumbing to mini-naps while sitting up, and nothing felt as good as diving between the sheets that night.

Scientists used to believe sleep was a period of downtime for the body, when it could rest and be fairly quiet, but that's now regarded as entirely false. Sleep is an extremely active time, and it's an absolutely critical process. Here's why we should start treating bedtime with respect.

How much sleep do we need?
I totally know the answer to this one, you're thinking. Every health-conscious woman knows it's eight hours a night. Nice guess, but you're wrong. Or you could be right. Confused? Scientists now agree that sleep needs vary from person to person and are likely based on genetics. Although eight hours may have you feeling perky, your gym partner might need 9% and your co-worker could get by with just six. Yet it's also possible that your co-worker only thinks she's getting by with six hours of sleep per night.

In a 2005 study that examined how sleep need (how much sleep your body requires to feel good and perform at its best) varies by individual, scientists from Brigham and Women's Hospital and Harvard Medical School (both in Boston) had subjects record how much they slept for two weeks and then brought them into the sleep lab for three days. During those three days the researchers had each subject try to fall asleep at two-hour intervals and measured how much the subjects slept overall. They found that the people who had reported sleeping the least during the previous two weeks fell asleep more often and more easily in the lab than those who regularly slept more, and all subjects slept more in the lab than they reported doing in their normal lives. The results indicate that subjects were quite functional at the typical sleep levels they reported, but they were likely living with a good degree of sleep debt.

Huh? Sleep Debt?
That's what scientists call the amount of sleep you miss every night you don't get your optimal amount of shut-eye. If you normally sleep 81/2 hours but then get only six hours one night, for example, you're considered to have 21/2 hours of sleep debt. The higher your debt, the worse you function during the day--and the drowsier you feel. Some scientists believe that if you feel the slightest urge to drop off during the day, even if you're engaged in the most boring task at work, that's a sure sign you're sleep-deprived. And while you can repay your sleep debt by getting adequate sleep several nights in a row, you can't "bank" sleep for a night when you know you're not going to get enough Z's. The key, then, is to make sure you regularly get the optimal level of sleep. How do you know what's optimal? It's the amount of sleep you get when you can wake up without an alarm and feel alert all day long.

Yeah, like that'll ever happen
Hey, you don't have to tell us. We know all about work deadlines and hitting the gym and helping the kids with their homework before squeezing in a few minutes with the significant other and then hitting the sack. But perhaps we should tell you what happens to your body when you don't get an optimal amount of sleep.
There's a long list of the ill effects of getting insufficient sleep. It includes things such as altered mood (as in terminally grouchy), day-time sleepiness (which can be dangerous if you're, say, behind the wheel) and worse:

Increased risk of diabetes: A study conducted by the GSF National Research Center for Environment and Health in Neuherberg, Germany, involving almost 8,300 people found that those who had trouble sleeping were more likely to acquire type 2 diabetes. This correlates with the findings of a study published in the journal Diabetes Care in 2006 that found similar results among subjects who slept either less than seven hours per night or more than eight hours per night. Although scientists aren't entirely sure why there's a link between diabetes risk and sleep dysfunction, they suspect it might have something to do with the next condition.

Increase in chronic, low-grade inflammation: We've discussed the hazards of inflammation before in the pages of this magazine, so you should know that the type that's bad is the internal kind you can't feel. That's exactly the kind that appears to be exacerbated by getting too little sleep. A study conducted at the Pennsylvania State University College of Medicine (Hershey) found that when 25 otherwise-healthy subjects were restricted to six hours of sleep per night for a week, they experienced an increase in levels of pro-inflammatory cytokines, cells that amplify the inflammatory response.

Association with higher bodyweight: Two studies published in 2005, one in the Annals of Internal Medicine, the other in the Journal of Clinical Sleep Medicine, examined the sleep records and body mass indexes of thousands of subjects. Those who were obese reported sleeping less each night than those who fell within the normal body mass range. Perhaps it has something to do with the next point.

Increases hunger and appetite: Leptin and ghrelin are two of the hormones that govern a person's hunger, appetite and satiety. In brief, ghrelin triggers hunger pangs, and leptin triggers satiety and speeds up metabolism. According to a 2004 study at the University of Chicago, sleep restriction resulted in decreased leptin levels, increased ghrelin levels and, therefore, a boost in appetite, meaning that sleep-deprived individuals are likely to eat more than those who are fully rested.

Okay, we get the point
We could go on. Sleep is thought to be a time when your body repairs much of the day's damage, so if you're not sleeping as much as you should, it's possible that your muscles aren't being repaired as well as they could. The brain benefits, too: Memories are mapped and learning is solidified during hours of sleep. People who are sleep-deprived have impaired coordination, less endurance and reduced strength than their well-rested brethren. The importance of sleep on health, fitness and overall well-being cannot be overstated.

As anyone who takes care of herself knows, the body is always trying to find and maintain balance. Run on a treadmill and your body will sweat to bring your core temperature back to normal. Eat a meal and your insulin levels rise to metabolize the glucose produced. But often the balance is delicate, and losing it can have a domino effect on all kinds of other bodily processes. Sleep is one of those delicate functions--so vital that the body will actively force it on you if you fight it too long. Our message to you? Be as vigilant about sleep as you are about your time in the gym. It's just as important to your health.

Sleep Stack
You know sleep is important, but that doesn’t make it come any easier. If you’re struggling to sleep, try these supplements.

>> Start by taking ZMA, a combination of zinc and magnesium, both of which are linked to relaxation and calming feelings. Take two capsules of standardized ZMA, or 20 mg zinc and 300 mg magnesium, 30-60 minutes before bedtime.

>> If the ZMA alone didn't work and you're not feeling drowsy, try melatonin. It's a hormone that governs sleep-wake cycles. Take 0.5-5 mg 30 minutes before bedtime.

>> Still not asleep? Valerian is an extremely powerful root that has sedative qualities. Take only if all else has failed and you're desperate to sleep. Take 200-400 mg right before bed.