Sleep is a polarizing topic – some people covet it, some people disdain it. Though regardless of your feelings, sleep is major! In fact, many health scientists consider it the most often neglected, yet most critical, factor to our health.

If you've ever stayed up late before a test only to sit down and have forgotten the majority of what you crammed in the night before, you know why sleep is important. If you've ever driven on interstate roads and felt yourself nodding off, you know why sleep is important. If you've ever left an awkward text unanswered only to reply days later with, "Oops sorry fell asleep!" (is that just me?) you know why sleep is important.

Learn all about the mysterious going on that our bodies experience during sleep, as well as methods you can easily implement to optimize your sleep! – You'll be a happier, smarter, and all around better, you!

What is sleep?

This may sound like a dumb question with an obvious answer, but unless you’re a sleep specialist (in which case, don’t read this article because you probably know everything) there are likely important details that you’re missing. Broadly, sleep is a cyclical state that is required for sustained life and is accompanied by variations in brain activity, hormone levels, and muscle relaxation.

Why is sleep important?

Although today sleep is often treated as an optional habit, it’s not. There’s even evidence to suggest that we can survive longer with a suboptimal diet than we can with suboptimal sleep! Sleep is integral in emotion regulation and memory, physical and mental stamina, repair of muscles and organs, weight optimization, and immune function (or in other words, everything).

Some really cool brain structures are involved in sleep!

via: Getty

These include the hypothalamus, thalamus, suprachiasmatic nucleus (SCN), brain stem, cerebral cortex, pineal gland, basal forebrain, midbrain, and amygdala.

The Hypothalamus, SCN, and Thalamus

These structures are humble in size (the thalamus is about an inch long and the hypothalamus about half an inch) but they boast a host of functions. Located in the diencephalon portion of the forebrain, the thalamus and the hypothalamus are a part of the limbic system, which drives our emotional processing. Within the hypothalamus lies a cluster of neurons called the SCN, which perceive light exposure and control our circadian rhythms, or the natural cycles our bodies experience in a 24-hour time frame (e.g. sleep!). The thalamus acts as a switchboard in the brain, relaying information from the spinal cord and sensory receptors to the brain for processing.

The Brainstem and Amygdala

The brainstem is located at the base of the posterior brain and communicates with the hypothalamus to moderate sleep transitions. GABA, a neurotransmitter that inhibits nerve activity, is produced by the cells in the hypothalamus and the brain stem. It’s thought that the brain stem also plays a role in sleep, inhibiting our limbs from moving while we dream. The amygdala is primarily used for emotional processing and becomes increasingly active during REM sleep, or the state of sleep associated with dreaming. 

The Cerebral Cortex, Basal Forebrain, and Midbrain

The cerebral cortex is the layer of grey matter that covers the surface of our brain and is integral in human intelligence. Sleep plays a major role in learning and recall, and communication between the cerebral cortex and other brain structures are critical to this end. The basal forebrain and the midbrain are other brain regions that are critical in circadian rhythms and the basal forebrain releases adenosine, a compound that is blocked by caffeine (thus, stimulating wakefulness).

The Pineal Gland

The pineal gland is located in the epithalamus, near the center of the brain and is approximately pea-sized. This structure is particularly interesting since it’s implicated in many spiritual practices due to the belief that it produces small quantities of DMT. That said, it also manufactures the hormone melatonin, which helps to synchronize our sleep-wake cycle.

What Happens When You Sleep?

This is where things get interesting! Sleep involves a cascade of cerebral and physiological mechanisms, but let’s begin with the brain. Sleep is divided into two categories of brain activity: non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. From here, NREM is composed of 4 stages of sleep, named Stage I, II, III, and IV – science is not very creative in their taxonomy, I know. Before exploring the stages of sleep, it’s important to understand the various brain wave types and what brain activity they’re associated with. Brain waves are literally electrical in nature, which is why science uses an Electroencephalogram (EEG) to measure them. Each of the five brain waves is defined by their frequency or the number of waves that occur during a specific time period. Frequency is measured in Hertz (Hz), so each brainwave is associated with a specific Hz range. Amplitude or the height of the wave is also used to describe brain wave activity.

Stage I Sleep

While wakefulness is characterized by beta waves (13-24 Hz), a high frequency, low amplitude wave associated with problem solving and alertness, when an individual is preparing for sleep the activity on their EEG reading slows. Alpha brain waves (8-12 Hz) predominate here, with ephemeral theta waves (4-7 Hz) occurring as well. Alpha waves are indicative of relaxation and theta waves imply a deeply subconscious and meditative state. Heart rate, the muscles relax, and body temperature drops during stage I sleep.

Stage II Sleep

Metabolic mechanisms continue to slow in stage II sleep, but another unique pattern of brainwave makes an appearance as well. Sleep spindles, or bursts of high-frequency activity, intersperse on an EEG read-out and although their function is not entirely understood, they are believed to play a crucial role in learning and memory consolidation. Sleep spindles are generated by the thalamic reticular nucleus (TRN) and other thalamic nuclei which have been shown to receive input from the cerebral cortex, relaying it to subcortical brain structures. In layman’s terms, it’s thought of as the brain’s switchboard, making it easy to see why it’s so deeply integrated with learning.

Stage III Sleep

Stage III sleep marks the beginning of what is termed as slow wave sleep (SWS). SWS involves delta waves, which oscillate at less than 4 Hz but maintain a high amplitude. As with sleep spindles, SWS is thought to be critical for memory consolidation and is also indicative of deep repair in the body and the brain. For example, glucose metabolism in the brain increases during stage III as well as the secretion of growth hormone (GH). If you’re wondering, it typically only takes one hour of sleep to enter SWS! A lot happens while you’re not aware, huh?

Stage IV Sleep

Stage III and IV were once grouped together, likely because both are heavily characterized by the presence of delta waves. That said, stage III sleep is comprised of about 20-25% delta wave activity, while stage IV is more than 50%. This is the deepest sleep you experience during the night.

REM Sleep

Rapid Eye Movement (REM) sleep denotes the back and forth eye movements that individuals often make during this stage of sleep. Brain activity more closely mimics that of a waking individual, and REM normally only lasts for about 10 minutes before the sleep cycles are repeated. Another interesting fact is that REM sleep decreases as we age, declining from about 8 hours at birth to only 45 minutes at age 70. As REM is associated with dreaming, this may help explain why we often exhibit worse recall of our dreams over time.

The Sleep Rollercoaster

Graduating from stage I to REM only takes about 70 to 90 minutes, so individuals will go through each stage several times while asleep. The first few cycles confer longer deep sleep stages while later cycles see a prolongation in stages I, II, and REM.

Cerebrospinal Fluid: The Brain’s Detox System

As mentioned, the brain undergoes repair during sleep but how it does so is unique. The blood-brain barrier is a semipermeable border that regulates what accesses the brain and what remains in the circulatory system. As such, the brain requires different cleansing mechanisms than the rest of the body. Enter cerebrospinal fluid or CSF. This is produced in the cerebral ventricles and is circulated throughout the brain during sleep in much higher quantities than while awake. Brain cells actually shrink during sleep, allowing CSF to flush into the interstitial space and clean out various waste products like amyloid plaques, which have been implicated in Alzheimer’s disease.

How to Get More Sleep

I hope I’ve convinced you just how important (and cool) sleep is. But what’s knowledge without application? Let’s cover some key methods that you can implement to increase not just your time in bed, but your sleep efficiency, or the length of time you are truly asleep.

Normalizing Circadian Rhythm

Good sleep doesn’t live inside a vacuum, it’s just one component of a large fabric of physiological processes that live on a 24-hour continuum, known as the circadian rhythm. Thus, understanding how and when to tweak certain habits during the day can reap a more restful night!

In the A.M you poop and eat.

At about 6 am, your body begins to pump out a stress hormone, cortisol. This is normal and helps you to wake up in the morning. At the same time, another hormone named vasoactive intestinal polypeptide (VIP) causes a host of other physiological reactions, including smoothing your trachea, stomach, and gallbladder. This is largely why we poop in the morning! VIP also causes a surge in the hunger hormone ghrelin, so eating breakfast within two hours of waking can help to reinforce our circadian rhythms. If you’re not a breakfast person there’s no need to force yourself to eat, but rather recognize that if you have hormonal imbalances it may be wise to do so, since this helps normalize any symptoms.

In the A.M. we also need sunlight exposure.

Sunlight exposure in the morning is another powerful way to support our circadian rhythms as it helps to boost serotonin, a neurotransmitter, and hormone that increases feelings of well-being. A morning stroll (5 to 20 minutes) in the sun also helps to regulate our cortisol fluctuations throughout the day, lowering levels at night. If you aren’t able to spend the time in the morning, drinking a small dose of coffee or green tea can help. Lastly, it’s important to fit in some sort of light movement in the morning, like yoga or simple calisthenics. Doing this helps boost brain-derived neurotrophic factor (BDNF) which elevates mood and increases learning.

The P.M. involves a lot of movement, movement, movement!

Although morning is a great time for some light movement, more intense exercise is recommended later in the day. 2:30 pm marks the approximate time that our bodies are primed for coordinated movement and enhanced reaction timing, so playing a ball game or other sport is best during this period. Near 5 pm our cardiovascular capacity and muscle repair pathways peak, making this a perfect time to lift weights or engage in high-intensity interval training (HIIT). Exercise helps to regulate hormones, meaning that you won’t be nearly as wired when it’s actually time to hit the hay. That said, intense exercise does increase the release of cortisol, so ending your exercise routine at least 3 hours before bed-time is wise.

In the P.M. we start to cool down.

Right around sunset, our body’s core temperature rises. What’s interesting about this is that in order for optimal sleep quality, our core temperature should actually be slightly lower than average. For this reason, it’s a good idea to keep your thermostat set to about 65 degrees and you may even take a cold shower (if you can handle it!). It’s also typical to experience a curb in appetite, as the hormone leptin is released around this time. Incidentally, abstaining from eating a few hours prior to bedtime is an effective way to improve sleep quality! After all, sleep is your body’s time to rest and repair and if it’s busy digesting food, it can’t perform these tasks as well.

In the P.M. we black out.

Right around 10 p.m. our pineal glands secrete that sacred sleeping hormone, melatonin. As such, it’s important to avoid blue and other forms of bright light leading up to bedtime because it artificially blunts the release of melatonin. Consider using blackout curtains or buying a sleeping mask to mimic this pitch-black effect that is so difficult to achieve in our modern society.

In the P.M. we need zen and zero sound.

When preparing for bed, also try eliminating extraneous noise and distraction. If you want to distill it down to a simple rule of thumb, think anti-stimulation. Try deep breathing, light stretching, meditating, reading, and even using noise-cancelling headphones to drown out any pesky city sounds.

In the A.M. is when you're body does the critical repair.

Between 2 am and 6 am, your body’s core temperature falls even lower, which catalyzes a host of repair mechanisms. The trick is, your body must have been asleep for up to 6 hours already! This means that if you go to bed late, you may not be benefiting from a lot of these important processes. Of course, everyone is different so it’s important to listen to your body and sync with what it’s telling you.

Quantifying and Biohacking

“Biohacking" is an interesting trend in the health sphere as of late, using technology to quantify our biology and in response manipulate relevant factors to improve our health outcomes. That said, consider investing in a device that can accurately track your sleep and provide you with feedback on its quality. The Oura Ring is reputable, but if you don’t have the cash laying around apps like Sleep Cycle are free to download and can provide some useful data on your sleep as well.

Learning More About Yourself

As mentioned, it’s important that you understand your body’s preferences and its unique circadian rhythms. Sure, it takes a little more effort up front but you end up saving yourself time and energy down the line. For a rough idea of how you should tailor your sleep cycles, consider this quiz that sleep doctor, Michael Breus, developed. If you’re really intrigued by this whole biohacking scheme, try using the platform that renowned circadian rhythm researcher Dr. Satchin Panda developed.

Supplements for Sleep

Insomniacs and light sleepers can probably all testify to popping melatonin pills galore at some point or another. But here’s the problem with that approach: melatonin is a hormone so unless you’re deficient, your body may build a tolerance for it in the future. Instead, try rotating a number of supplements that are safe and proven effective. For example, Valerian Root promotes sleep by preventing the metabolism of GABA and also contains specific antioxidants that appear to have sedative properties.

Cuddle Up

This ties into other winding down practices we’ve covered, but it deserves its own highlight because of the wonderful hormonal effects it has. Touch has actually been studied extensively and found to greatly improve sleep quality, likely due to an increase in the hormone oxytocin. Oxytocin lifts and calms the mood, and acts as a powerful antioxidant and anti-inflammatory. So grab your honey (or friend, or pet) and give them some love and attention, you’ll benefit from it!

The Curse of the "Toss and Turn"

If you’re someone who frequently wakes up in the middle of the night, don’t sit in bed and stare at the ceiling, praying for sleep to come. This only causes your mind to go into what’s called the default mode network (DMN), or a state that keeps you awake and anxious. Instead turn on a dim light and read or write. This allows your brain to focus on something specific while only requiring a low level of activity so that when you’re ready, you can fall back asleep.  

Sleep On It

That’s quite the case for sleep, if I do say so myself. You don’t have to integrate every strategy to sleep better, but knowing what’s out there is important so that you can tailor it to your needs.