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People often say:

“Eat big, train hard, and you will grow.”

While not inherently wrong, this statement lacks one fundamental: Sleep.

Today, we’ll go over the critical importance of sleep and why you need it if you want to grow optimally.

Sleep’s Impact On Vital Muscle-Building Hormones

Sleep directly impacts muscle growth thanks to its effects on two important hormones: testosterone and IGF-1.

Research shows that sleep deprivation reduces testosterone and IGF-1, which is not good (1, 2, 3).

First of all, testosterone plays an essential role in muscle growth. The hormone drives the process by binding to androgen receptors and going to cells’ nucleus to promote protein synthesis. The hormone also stops proteins that inhibit the mTOR pathway – the primary metabolic pathway responsible for physical development.

IGF-1 (insulin-like growth factor 1) is also involved in the mTOR pathway and promotes protein synthesis (4). 

By not getting enough sleep, you lower levels of these two hormones, making their effects on the body less pronounced. 

But that’s not all. Have you ever heard of cortisol – the stress hormone? That’s right, sleep impacts it, too.

Acute spikes in cortisol occur and are completely normal. For example, when you wake up in the morning, cortisol spikes and gradually decreases as the hours go by. But chronic elevation of cortisol leads to tissue breakdown. Specifically, too much cortisol prevents your body from building muscle and accelerates protein breakdown (5).

The bottom line is this:

Sleep deprivation has a direct impact on muscle growth. If you want to grow optimally, you need to get your sleep – there is no way around that.

Sleep’s Impact On Our Performance, Motivation, and Effort

Beyond the subtle way sleep deprivation stops us from building muscle, it also has some apparent effects. More specifically, not getting enough sleep decreases our performance, saps our motivation, and prevents us from working as hard (6).

So why is that such a problem? Research shows that training volume – the amount of work we do in the gym – is the most critical factor for muscle growth (7). In other words, the more work we do, the more growth we can expect. Of course, this is up to a point, and we can overtrain if we aren’t careful.

Plus, training effort is also essential for muscle growth – we need to push ourselves hard enough to cause disruptions at a molecular level (8).

By not getting enough sleep, we simply can’t train as effectively. We feel tired, irritable, and unmotivated.

The Bottom Line on Sleep

Yes, sleep is hardly an exciting topic. For the most part, we care about other, more fun subjects like exercise selection, picking the best split, and so so.

And yet, sleep is vital to get enough of.

The good news? You don’t need to be a sleep expert to optimize it. You mostly need to remember one simple thing:

Make sure to get at least seven hours of sleep per night. If possible, aim for eight.

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