Why can’t you sleep? Sleepless nights are a common problem and the causes are numerous. Aside from the obvious causes of sleeplessness — a noisy environment, being sick, congested, or otherwise uncomfortable — there are many people out there who have trouble sleeping and can’t nail down what’s disturbing their rest.

I’ll offer a common explanation for why many people have trouble sleeping. It’s not the only explanation by any means, but I see it in patients frequently enough that it warrants special attention.

Part of the problem is what we accept as “normal”. I can’t tell you how many times I’ve heard people say something like, “Oh yes, I sleep fine. I get up two or three times a night, but it’s no big deal.” Getting up two or three times a night is not normal. It may be common, but it is definitely not normal.

Part of our task, then, is to understand what a truly normal sleep pattern looks like, both from a practical and a physiological standpoint. Once we’ve done that, figuring out how one individual is straying from this path is a much simpler task.

For normal sleep, the most obvious thing to point out is that we should sleep through the night without interruptions. Many people assume that they wake up throughout the night because they have to go to the bathroom, and not the more likely explanation, which is that after awakening, they notice an urge to empty their bladder. In other words, their usual pattern of waking up several times a night gives their body the opportunity to urinate. If they were sleeping more soundly, the need to visit the bathroom would be less pressing.

Getting to sleep should also be relatively effortless. Overly long relaxation rituals, or worse, self-medication with prescription, over-the-counter, or over-the-bar depressants should not be necessary. If you regularly climb into bed, shut your eyes, and then toss and turn for an hour or more before finally falling asleep, something is not right. You should be able to stay asleep for six hours or more. Anything less is probably inadequate.

So what makes us sleep? There is plenty of research and many ideas on the topic. One of the best known theories, and one that seems to hold true clinically, is that a hormone in the brain called serotonin is largely responsible for sleep. As long as the brain pathways for this hormone are working properly, sleep ensues. For the sleepless, we want to know what might interfere with the brain’s ability to produce or utilize this hormone.

Let’s go back to the obvious. We all intuitively know that we can’t sleep when we’re “stressed”. But why? Sure, you may be preoccupied by thoughts, but how do these stressful ideas change your brain chemistry so that you can’t sleep?

That’s where another hormone called cortisol comes in. Cortisol is known as the “stress hormone”. It is released throughout our bodies when we are under any type of stress, be it psychological, chemical, or structural. It is also one of our primary blood sugar hormones. This means that any time we don’t have enough blood sugar to fuel our activities, cortisol is utilized to raise our blood sugar levels so we can handle whatever tasks our bodies are presented with.

Cortisol levels are highest right after we wake up — that is, right after we’ve finished (hopefully) 6-8 hours of sleep, during which time we typically don’t eat or drink. Cortisol is secreted to keep feeding your brain and other vital organs with the blood sugar, or glucose, they need to survive. Normally cortisol levels are highest right after you wake up, and begin to lower right after you eat breakfast, giving your body its first jolt of glucose.

What does this have to do with sleep? Well, we know that serotonin is associated with sleep. We also know that we can’t sleep when we’re stressed. Serotonin levels happen to be inversely related to higher levels of stress and thus, higher levels of cortisol. This means that anything that might raise your cortisol levels will correspondingly lower your serotonin levels, interfering with your ability to sleep.

Interestingly, part of cortisol’s normal, 24-hour cycle involves a spike in its levels around 3 am, give or take an hour. This is a very common time for people with sleep trouble to awaken.

Those with high daytime levels of cortisol are easy to spot. Remember, cortisol is a blood sugar hormone. Part of the problem, however, seems to be that the energy we derive from blood-sugar produced by cortisol tends to be edgy and anxious. Those with high cortisol typically crave sugar or alcohol late in the evening. The alcohol and sugar give a quick jolt of glucose to rapidly drop cortisol levels. This helps remove the edginess and allows serotonin to rise, letting sleep ensue.

Lack of sleep is frequently not the only symptom. Low levels of serotonin affect us in a number of ways. Perhaps the most well known effect of too little serotonin is depression. Serotonin is the hormone that popular antidepressants like Prozac and Zoloft work on. Their job is to artificially elevate serotonin so that your mood is not adversely affected. Your gastrointestinal tract is also almost entirely dependent on serotonin for healthy, regular function. Thus, sleeplessness and a sluggish gut frequently go hand in hand.

All of a sudden we have a plan of attack for figuring out how to sleep better. If we can narrow down the main things that tend to raise our cortisol levels, we can reduce the total amount of stress our bodies are under, raise our serotonin levels, and put ourselves back on the road to a good night’s sleep.

Luckily the culprits are relatively clear. Essentially, anything that increases our stress levels, in any form, will also raise cortisol levels. Our task is to find and treat the actual culprit of depressed serotonin levels so that getting to sleep by artificial means is unnecessary.

Next time, we’ll talk about the myriad ways our serotonin levels get disturbed and, more importantly, what we can do about it!