last updated October 20, 2021

Why Sleep Is Important and How to Sleep Better

by Rob Arthur

Contrary to what you may have heard, sleep isn’t for when you’re dead.

In this article, we’ll talk about what sleep is, why it’s important, its benefits, and how to sleep better.

If you have any questions at the end, let me know in the comments 🙂

What is sleep?

Sleep is not just some passive absence of wakefulness to allow for rest.  

It’s a highly organized, active process that follows a regular, cyclical pattern that involves changes to our body’s organs (1).

Sleep is typically organized into two main stages (2):

  • Non-rapid eye movement (NREM)
  • Rapid-eye movement (REM)

The NREM stage comprises four additional substages – N1, N2, N3, and N4.

Each NREM and REM stage represents a different pattern of brain activity, blood pressure, body temperature, heart rate, breathing, hormone secretion, and muscle tone.

We’re still learning what actually happens during sleep.

However, we’re fairly confident its purposes extend beyond any one specific function.

Why is sleep important?

Sleep is essential for development, energy conservation, brain waste clearance, immune response, cognition, performance, and disease (3).

There’s quite a bit of research demonstrating its connection to a variety of health outcomes.

Associations with disease

Poor sleep has been linked to dysregulated immune response (4), non-alcoholic fatty liver disease (5), and systemic inflammation (6).

It’s also a risk factor for cognitive decline and dementia, including Alzheimer’s (7), and mood disorders (8).

When it comes to sleep, we often think longer is always better and shorter is always worse.

Most of the time, that rule of thumb will serve us well.

However, it can be difficult to tell exactly what our sleep patterns might say about our health.

For example, two large meta-analyses found correlations between both short and long sleep durations with a variety of disease conditions.

One linked short sleep duration to increased risk for diabetes, hypertension, cardiovascular disease, coronary heart disease, and obesity (9).

The other linked long sleep duration to increased risk of diabetes, cardiovascular disease, stroke, coronary heart disease, obesity, and overall mortality (10).

Furthermore, it appears many disease conditions share a bidirectional relationship with poor sleep.

For example, there is strong evidence sleep disturbances can be causes and effects of mental health conditions.

Examples include depression (11), anxiety, obsessive-compulsive disorder, and post-traumatic stress disorder (12).

That all being said, there’s a good chance that, while long sleep can be a sign of a problem, a deliberate effort to sleep longer likely won’t create one.

That is, if you were to sleep longer on purpose, you likely would improve your health.

A deliberate effort to shorten sleep, on the other hand, most likely will have the opposite effect.

In fact, this is pretty much unequivocally what experimental, rather than correlational, studies demonstrate.

So, let’s take a look at some of these interventions to get a better feel for the relationship between sleep and health.

We’ll start with your efforts to get leaner, bigger, or stronger.

Body composition

When setting out to lose fat, build muscle, or get stronger, most of us look at nutrition and training.

However, we often overlook sleep.

Doing so, we neglect a powerful tool for getting the most bang for our diet and exercise bucks.

For starters, sleep deprivation appears to drive appetite for high-calorie foods (13).

This is due to changes in activity of certain brain regions involved with appetite.

As little as one night of sleep curtailment appears to promote increased hunger, food cravings, food reward, and larger portion sizes (14).

Sure, you might be able to white-knuckle your way through these changes in appetite and see some progress on the scale.

However, any weight you lose or gain might actually leave you looking and feeling worse than before.

For example, a 2018 experiment showed that sleep restriction by an hour a night during weight loss led to less fat loss and more muscle loss (15).

Sleep extension, however, appears to improve weight loss efforts.

In a 2020 experiment, longer sleep extension led to greater weight loss, reduced waist circumference, and lower insulin levels (16).

We see similar detrimental effects on muscle growth and strength gains.

For instance, a 2018 systematic review concluded that consecutive nights of sleep restriction, but perhaps not a single night of deprivation, appears to impair strength during resistance training (17).

Most notably, multi-joint compound exercises appeared to suffer the most.

Furthermore, in a 2020 experiment, five nights of sleep restriction appeared to reduce muscle protein synthesis (18).

Similarly, in a 2021 experiment, a single night of sleep deprivation reduced muscle protein synthesis by 18%, increased plasma cortisol by 21%, and decreased plasma testosterone by 24% (19).

These effects on body composition are reflected in other markers of metabolic health.

Metabolic health

Along with weight gain and loss of lean mass, poor sleep can promote increased appetite and caloric intake, reduced insulin sensitivity,  impaired glucose control, and cortisol dysregulation (20).

Experiments in which sleep is extended, however, have resulted in improved insulin sensitivity, leptin profiles, appetite, desire for sweet and salty foods, sugar intake, and protein intake (21).

In addition to body composition and metabolic health, we can see effects on athletic performance as well.

Exercise and athletic performance

Sleep restriction and deprivation have been shown to negatively affect both the mental and physical aspects of exercise and sports performance and recovery (22). 

As you might have already guessed, sleep extension appears to have the opposite effects (23).

Sleep doesn’t only affect your physical health, which we’ve been focused on so far.

It also impacts your ability to think clearly and perform mentally.


Neuroimaging studies show sleep deprivation to impair attention, focus, working memory, risk/reward processing, impulsivity, emotional processing, and learning (24).

Correcting sleep deprivation, on the other hand, can improve cognitive function, attention, memory, and executive function (25).

All of this suggests that while longer sleep can be a sign of disease, it’s not likely it’s a driver of disease.

Short sleep, on the other hand, doesn’t appear to offer much benefit in any situation.

Now we’ll discuss what you can do to help your sleep habits work for you, not against you.

How to sleep better

There are steps you can take before bed – often referred to as “sleep hygiene” – to prepare your body for a restful night.

Sleep hygiene

Set a bedtime that allows for 7 hours of sleep, establish a relaxing bedtime routine, keep your bedroom quiet, comfortable, and cool, and use your bed only for sleep and sex (26).

You might also aim to get regular exercise, manage stress, reduce noise, set a consistent bedtime, and avoid caffeine, nicotine, alcohol, and daytime napping (27).

Light exposure is another factor to which you might want to pay attention.

Get plenty of bright light early and throughout the day, while minimizing bright light – especially from artificial lighting, smartphones, and screens – at night (28).

If you must use screens at night, consider wearing amber-colored blue light blocking glasses for 2 hours before heading to bed (29).

You may also want to pay attention to your eating habits.

Make sure you’re eating enough, particularly protein and carbohydrates, and consider supplementing with melatonin, GABA, or glycine (30,31).

If none of this works, consider if other health issues are at the root of the problem.

Underlying health issues

We mentioned earlier that sometimes sleep issues are symptoms, rather than drivers, of disease.

So, if you’re experiencing sleep issues, consider other aspects of health you might want to address.

Eat well, enjoy physical activity, manage stress, and spend time with people you love.

Reach out to a physician or other professional when necessary.

We all need help sometimes, and there’s no shame in that.

Let’s wrap this thing up with some tips on how to start putting all this into practice.

What to do now

You don’t have to take all of these steps at once.

As a matter of fact, you might find taking one at a time to be more effective.

Such an approach might help you better identify which steps help and which ones don’t.

After all, different strategies work and don’t work for different people.

Ideally, you’ll start with something that seems easy and manageable.

Then, pay attention to any changes you observe.

Do you fall asleep faster or stay asleep longer?

Are you waking up feeling more refreshed?

Do you have more energy?

Is your mood improving?

Are you more focused and alert?

Has your training progress improved?

If you find a specific strategy helpful, keep it up.

If not, let it go.

Find what works for you.

This may take time.

This may take effort.

It will be worth it.

You’re worth it.

You’ve got this.


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