“I can go on 6 hours of sleep, no problem”, a lot of people tell me proudly, even puffing their chest out. As if sleeping less is some kind of honour, accomplishment or distinction. Just because sleep deprivation isn’t killing you instantly doesn’t mean it’s actually good for you. In fact, we know that sleep deprivation isn’t good for us, and in this newsletter, we’ll talk about how poor sleep affects your hormones.

Original source: here.

Insulin and Blood Sugar 

Let’s start with this one, since it’s the single most controllable hormone in the human body.

Insulin is the hormone you release when your body’s “thermostat” detects that blood sugar is too high.

In a healthy person who eats a high-carbohydrate meal, blood sugar will rise, and subsequently, insulin will rise to bring blood sugar back down.

In a person who is sleep-deprived, blood sugar will rise, and subsequently insulin will rise. But the cells don’t hear the message as well, and so blood sugar doesn’t fall as well as it should.

So you may be eating a great diet, but if you don’t sleep well, that great diet will still elevate your blood sugar levels more than it should.

In one study, 6 young males were restricted to 4 hours of sleep for 6 nights, and their glucose tolerance (a measurement of how many carbohydrates you can tolerate) was measured. The results: glucose tolerance was decreased.

Now, you may be proudly patting yourself on the back, thinking “I get a healthy, 8-9 hours of sleep per night. I’m good.” Not so fast, buster. Quality is just as important as quantity.

There is one stage of sleep called REM (Rapid Eye Movement) sleep. This is a phase of sleep when your body is literally paralyzed, but your eyes are moving under your eyelids as if you’re awake. This stage is particularly crucial for mental restoration.

In one study, researchers manipulated subjects’ brain waves so that they still slept for 8-9 hours per night, but without REM sleep. The results: once again, glucose tolerance was decreased. Also, their blood sugar and insulin in the morning were both increased.

The lesson: both quality and quantity of sleep are important.

Growth Hormone and Cortisol 

Growth hormone is the hormone you release to repair your body. You exercise, and therefore create very small damage to your muscles. The goal of the damage is to stimulate the body to repair that damage, and come back stronger than before. That’s a desirable effect. What’s responsible for recovering from this damage? Growth Hormone. What’s the single greatest stimulus for growth hormone release? Deep, restful sleep.

No deep, restful sleep for you? Expect slower recovery from exercise, less mental clarity, and even dark circles under your eyes. Oh yeah, and accelerated aging.

Cortisol is the hormone you release throughout the day, and more so during times of either mental/emotional stress or physical stress. It’s naturally high in the morning, and goes down throughout the day, and that’s the way we want it.

The problem happens when you don’t sleep well, or you don’t sleep enough. That causes cortisol to behave undesirably in different ways. In one person, it may cause an elevation in cortisol all throughout the day. In another person, it may cause a reversed cortisol rhythm. Meaning, it’s low in the morning, and high in the evening.


So these are some of the hormonal consequences of poor sleep. And I’ll bet you’re reading this article at 3AM, aren’t you? Go to sleep!