The Sleep Science Guide: Improve Your Performance with Good Sleep
Get Good Sleep Using Science!
Good sleep is important. Sleep has evolved to be one of our primary functions and dictates the quality of our waking days.
We sleep for over a third of our lives, and our brains continue to work while we sleep. It is a fundamental activity that has a huge impact on the quality of our waking life. We’ll discuss the science of sleep, what happens behind the scenes while we’re unconscious, and ways to make our sleep better.
After reading this article, you will have a clear understanding of what science knows about why and how we sleep. You will also be equipped with practical strategies to get good sleep every night. You’ll be able to tackle the next day firing on all cylinders.
- The Science of Sleep
- How Sleep Works
- How to Sleep Better
(links will jump to the section)
The Science of Sleep
Sleep serves multiple purposes that are essential to your mental and physical health. It actively maintains your mind and body.
Since good sleep is vital to our health, we will explore what science has discovered about this important process. We will look at why we sleep, what it does for us, how much we need, and what happens when we dont get enough.
Why We Sleep
Sleep Restores Our Brains and Bodies
During each day, our brain cells use up the day’s energy resources and create byproducts. Sleep clears away these waste byproducts to keep them from overloading the brain.
It does this through activating our glymphatic system, which functions as a waste clearance pathway for our central nervous system.
Sleep also repairs our bodies. During the first half of the night, our bodies release growth hormones that break down fat and repair our tissues. It also replenishes our energy for tomorrow.
Sleep is just as important for overall health as diet and exercise
Carl Hunt, MD, director of the National Center on Sleep Disorders Research
Sleep Helps Us Consolidate Our Memory
Sleep restructures our brain based on thoughts, experiences, and skills we learn and use during the day. It helps crystallize relevant short term memories into long term memories.
There are several types of memory and they are all consolidated by sleep.
Explicit memory involves conscious and intentional remembering of information. Information that unconsciously enters the memory are implicit memories
Declarative vs Procedural Memory
Declarative memory requires the conscious memorization and recall of factual information. Examples include words, dates, events, people, and concepts.
Procedural memory usually involves repeating an activity until all of the relevant neural systems work together to automatically produce that activity. Procedural memories can be used without the need for conscious control or attention. Many people refer to this as muscle memory.
Semantic vs. Episodic Memory
Semantic memory refers to a structured record of facts, meanings, concepts. An example would be remembering fun facts and trivia.
Episodic memory deals with experiences and specific events from your own life in the order it happened. An example of episodic memory is recalling a story that happened when you were younger.
As we go throughout the day, our brain produces adenosine. It is responsible for building up sleep pressure. The longer we stay awake, the higher our sleep pressure levels increase.
Caffeine actually works by blocking adenosine receptors. Contrary to popular belief, caffeine does not actually give you energy. It simply makes you not feel as tired from your sleep pressure.
Sleep is the chain that ties health and our bodies together
Benefits of Good Sleep
Good Sleep rejuvenates our energy. It can promote faster healing and help prevent depression. You may even find it easier to lose weight.
With a good night’s sleep, you can even reduce your overall stress. Sleeping on a complex or creative problem overnight can help your brain work on solving it!
Sleep is essential for learning and developing skills. Check out this video on The Benefits of a Good Night’s Sleep. (5:30)
How Much Sleep do we need?
We’ve explored how important sleep is and what it does for us, but how much sleep do we actually need?
Let’s take a look at a collaborative sleep experiment by researchers at Washington State University and the University of Pennsylvania. They took a group of adults who average 7-8 hours of sleep per night. One group stayed awake for 3 days straight. The rest slept for either 4, 6, or 8 hours a night for 2 weeks. They had their mental and physical performance tested throughout the experiment.
The experiment had 2 key discoveries.
Sleep deprivation builds up over time as sleep debt. Sleep debt is the cumulative effect of not getting enough sleep. After the first week, a quarter of the six-hour group fell asleep at random moments throughout the day. After the second week, the same group had performance deficits similar to the group that didn’t sleep after 48 hours. It’s worth reinforcing: if you only sleep for 6 hours a night for two weeks, your mental and physical performance will drop to the same level as if you haven’t slept for 48 hours straight.
The second greatest discovery is that the participants didn’t notice their own decline in performance. When they graded themselves, they thought that their performance only declined for a few days and tapered off. In reality, they were getting worse with each passing day. In other words, we are pretty poor judges of our own decrease in performance, especially while we are experiencing it.
According to a wide range of studies, the tipping point where we start to accumulate sleep debt is usually under 7 hours. Generally speaking, experts agree that 95% of adults need to sleep between 7 to 9 hours each night to perform their best. Most adults should aim for at least eight hours each night. Children, teens, and older adults typically need a couple hours more.
Your life is a reflection of how you sleep, and how you sleep is a reflection of your life.
Dr. Rafael Pelayo
What Happens During Sleep Deprivation
Sleep experts often compare sleep-deprived people to drunk drivers. There are similarities between both. As with drunkenness, one of the first things we lose in sleep deprivation is self-awareness.
When we lose sleep, our learning, memory, mood, and ability to respond to our environments are impaired. We become more impulsive and irritable. Our immune systems will weaken, making us more prone to illness.
Overall, short-term sleep deprivation causes us to lose our mental and physical performance. Over longer periods of time, it can really chip away at our health.
These videos provide a good overview on the effects of sleep deprivation:
What would happen if you didn’t sleep? (4:20)
What Sleep Deprivation Does To Your Brain (3:30)
How Sleep Works
In understanding sleep, it is important to know the different stages of sleep that we cycle through before waking up. It is also important to understand the two biggest internal drivers of our sleep regulation: the circadian rhythm and sleep pressure. External factors can also play a large role in both regulating or disrupting our sleep.
The Sleep Cycle
There are 5 stages of sleep that determine the quality of your sleep. Each stage brings us deeper into our slumber.
This infographic by fix.com provides a good overview of the different stages:
(click here for the original article on sleep routine)
After we finish the fifth stage, we’ll cycle back through the stages. Each cycle lasts about 90 minutes.
It is best to plan to wake up after a full cycle. If you try to wake up during the fourth or fifth stage, you will have a tremendous amount of sleep inertia.
The two stages that are the most important to us are deep slow-wave sleep, and Rapid Eye Movement sleep (REM.)
Our Sleep Cycle During a Normal Night:
During deep sleep, our bodies are very relaxed. Our pituitary gland releases growth hormone. This growth hormone stimulates muscle growth and tissue repair. When you are physically active, the deep sleep stage helps your body recover. This is why you’ll often hear about professional athletes sleeping a bit longer every night.
In contrast, REM sleep does for your mind what deep sleep does for your body. This is when your brain dreams and processes information. It clears out irrelevant information and consolidates your memory.
These two stages are vital to your health. Deep sleep helps you recover physically while REM sleep helps you recover mentally.
Your Circadian Rhythm
The circadian rhythm is a 24-hour cycle that regulates sleep and wakefulness. Our circadian rhythms are controlled by our body’s internal clock, which is largely driven by cortisol and melatonin.
Your Internal Clock
Your internal clock is scientifically known as the suprachiasmatic nucleus (SCN) which is located in your brain’s hypothalamus. It turns out that if you remove and isolate the SCN in a lab, it still reliably turns on and off every 12 hours. Interestingly enough, this happens at the individual cell level rather than as a system.
The System Behind Your Internal Clock
Cortisol: The Stress Hormone
In general, our bodies release cortisol in response to stress. In the context of sleep, cortisol gets your body ready for the stress of waking up.
While we are awake, our cortisol levels oscillate hourly. They peak the highest when we wake up, after lunch, and after dinner.
Our SCN and cortisol have a direct 2-way relationship. Cortisol both controls our internal clock and is controlled by our internal clock. This means having high levels of cortisol from stress can disturb our sleep, and disturbed sleep can disrupt our cortisol levels.
When we have issues with our natural cortisol cycles, we will notice irregular emotional responsiveness as well as low energy and enthusiasm.
Melatonin: The Darkness Hormone
Melatonin is produced by the pineal gland located near the center of the brain. The pineal gland is roughly the size of a pea. The melatonin that it produces acts as the opposite of cortisol and is driven by our biological clock.
It is often referred to as the “darkness hormone” because it is associated with nighttime behavior. Melatonin levels start increasing when the sun goes down and peaks at night. It promotes sleep in humans and diurnal creatures. In nocturnal creatures, it promotes activity.
Measuring melatonin levels can reliably tell where the biological clock is during the phases of your circadian rhythm. This is useful because we can’t measure our SCN activity directly.
The Cortisol and Melatonin Cycle
When our circadian rhythm falls out of sync, we often get poor sleep. While we are awake, we are prone to needing naps, feeling fatigued, and poor performance.
This is commonly experienced by people who get jet lag from traveling long distances. People who work night shifts can fall out of sync with their circadian rhythms. It takes an average of 6 days for them to adapt to their new schedules.
Restless nights can even make us more likely to get into car accidents. A report by the AAA Foundation for Traffic Safety found that driving with 4-5 hours of sleep is similar to driving with a blood-alcohol content at or above the legal limit.
Our circadian rhythms alone are not enough to cause and regulate sleep.
We briefly discussed how sleep pressure builds up with adenosine. The longer we are awake, the stronger the desire and need to sleep grows, as well as the chance of falling asleep. On the other hand, the longer we sleep, the more the pressure to sleep dissipates, and the likelihood of waking up increases.
There are many external factors that can impact our quality of sleep. Light and temperature can influence our sleep time and duration. Our sleep can also be altered by food consumption, drugs, and other social factors.
The Power of Light
Light has a large impact on our circadian rhythm. It synchronizes our internal clocks with the external time from the environment.
Our eyes have 2 fundamentally different functions. They detect images and also give us an overall impression of the amount of brightness in our environment. Our eyes’ rods give us black and white vision while our cones give us color vision. On the other hand, our ganglion cells collect light information and fires it down a non-visual pathway to our internal clock. We can lose our vision from all of our rods and cones and still be able to regulate our internal clock.
Both light and melatonin have the ability to advance or delay our internal clocks.
Food and Drugs
There are some foods and drinks that can help encourage drowsiness and sleep. These often have tryptophan, which is found in bananas, seeds, tuna, turkey, yogurt, and milk. The same goes for foods that are high in carbohydrates like cereal or bread.
Some foods may have the opposite effect and keep you awake at night. Foods that contain tyramine such as ham, bacon, pepperoni, eggplant, raspberries, avocado, or nuts can have this effect. It helps to plan accordingly.
Certain psychoactive drugs such as marijuana and alcohol act as sedatives that encourage sleep. Some of these depressants may also inhibit REM sleep and lead to disrupted sleep.
On the other hand, stimulants such as caffeine, amphetamines, ecstasy, cocaine, and nicotine can be used to reduce or delay sleep. They can also have their own unfortunate side-effects.
Social factors can shape how we sleep. Stress from daily life can directly hinder our ability to go to sleep and the quality of our sleep.
With busy schedules, our alarm clocks wake us up for the day. Whether it’s for school or work, we often wake up early regardless of how much good sleep we get, or where we are in our sleep cycle.
Between home life with family and work, it helps to actively reduce social stress in order to reduce troubled sleep.
Stress at Home
Troubling family relationships can impact sleep. This goes for immediate family (such as spouse and children,) as well as with parents and siblings. The National Survey of Midlife Development in the United States suggests that frequent family tension and poor emotional support can both be strongly associated with disturbed sleep.
Stress at Work
Workplace stress can “follow workers home” and make us restless. The sleep loss can also come back to affect work performance.
Poor sleep can also make us rather vulnerable to making mistakes. Night shift work accidents have caused oil spills and chemical plant disasters in the past. Some medical professionals are required to work up to 96 hours in a week, and sleep loss makes them highly prone to making medical errors.
How to Sleep Better
There are a handful of ways to actively improve the quality of our sleep.
The practice of consciously following daily guidelines to control these internal and external factors and get better sleep is known as “sleep hygiene.” We will dive into good sleep hygiene habits, activities, and ways of avoiding sleep disruption.
General Sleep Hygiene
Stick to a Consistent Sleep Schedule
There are three main factors that influence how well you sleep: intensity, duration, and timing. Intensity refers to the amount of time you spend in deep sleep and REM sleep. Duration is how long you actually spend asleep. Timing is simply when you start sleeping.
The two main factors that we have the most control over are duration and timing. If you wake up around the same time every day, then your sleep duration is pretty much determined by when you go to bed. If you improve the timing of when you sleep, you will usually improve the duration as well.
How you sleep tonight also depends on how you slept last night. The best thing you can do to sleep better is to follow a regular sleep routine. This includes weekends and days off. This helps train your biological clock to keep your circadian rhythm steady.
You also want a regular pattern of light and dark exposure. You can stay in sync easier by opening the shades or getting sunlight right after you wake up.
Keep a Sleep Journal
When you keep a record of your sleep, you can see how habits affect your rest. You will also see how implementing new activities improve your rest and which are the most effective.
Try to track:
- When you go to bed
- How long it takes to fall asleep
- How many times you wake up during the night
- How you feel in the morning
- Which activities you implement or avoid
Comparing daily activities with your sleep patterns can reveal where making adjustments will help the most. Look for areas to improve your habits to promote good sleep.
There are apps that can track your sleep and wake you up when you are in your lightest sleep stage. (See Lifehacker’s Five Best Sleep Tracking Gadgets or Apps)
Create a Sleep Routine
We can’t simply switch on or off sleep. It takes some time to ease into it.
We want to give our bodies enough time to transition from our active days to encourage bedtime drowsiness.
Bedtime rituals are particularly important for children, especially when they reach the point where they resist bedtime and have a harder time falling asleep.
The following activities can help you relax and wind down for better sleep.
Activities that Promote Good Sleep
Maintaining Good Nutrition
What we eat can have a large role in how we sleep. This article by Mind Body Green covers 9 of the most important nutrients to have in our diet for good sleep:
2. Vitamin C
6. Vitamin D
9. Vitamin B6
In addition to these nutrients, we want to make sure that our evening meals are not too light or too heavy. Foods with tryptophan that cause drowsiness are better for dinner. On the other hand, foods that have tyramine that keep us awake are better for breakfast and lunch. It also helps to eat at least two or three hours before sleeping.
Exercise improves the length and quality of your sleep. This is especially true with cardio.
Appalachian State University studied people who exercised at 3 different times: 7 AM, 1 PM, and 7 PM. They found that the people who exercised in the morning spent the most time in deep sleep, slept more, and had more efficient sleep cycles.
Morning exercise helps reset our cortisol rhythm.Even 5-10 minutes of exercise in the morning has a meaningful impact on the quality of your sleep at night. It makes it easier for your brain and body to power down at night.
Even 5-10 minutes of exercise in the morning has a meaningful impact on the quality of your sleep at night. It makes it easier for your brain and body to power down at night.
However, we want to avoid exercising within a few hours before bedtime. The mental and physical stimulation can leave our nervous systems feeling wired and makes it more difficult to relax.
There are several ways to use essential oils to aid sleep. You can apply the oil directly to your skin. You could also add a few essential oil drops to a water spray bottle and give your pillowcase a spritz. The most popular method is to use an essential oil diffuser to dispense the aromas.
Relaxing Music & Sounds
Ambient nature sounds such as a rainfall or stream can help you relax. It may take some experimentation to find what works best for you. In general, you want sounds that blend into the background rather than draw your focus.
There are sound machines available that are designed to gently guide you into sleep.
Lower the Temperature to Keep Cool
Most people sleep best in a cool room. When your body begins to cool down, it signals your brain to release sleep-inducing melatonin, so you’ll start feeling drowsy. The ideal temperature range is usually between 65 to 75°F.
Breathing Exercises, Meditation, and Yoga
A study by the American Academy of Sleep Medicine followed the effects of meditation on chronic insomniacs. They practiced 20 minutes of morning meditation daily for 8 weeks. At the end, they were no longer clinically considered insomniacs.
They had improvements in sleep onset and duration, as well as less sleep disturbance.
Breathing deeply helps reduce your heart rate and blood pressure. Meditation and yoga are both based on breathing. One focuses more on your mind and the other on your body.
Regardless which activity you choose, steady rhythmic breathing will help release endorphins and relax your body.
Preventing Sleep Disruption
Apart from health issues, nicotine can lead to poor sleep. Nicotine interferes with your sleep as a stimulant.
Smokers often experience withdrawal pangs at night and are 4 times more likely not to feel as well rested after a night’s sleep than nonsmokers. Smoking can exacerbate sleep apnea and other breathing disorders, which can also hinder a good night’s rest.
Allen Carr’s Easy Way to Stop Smoking is a fantastic book and resource on the topic. Allen Carr has helped over 10 million smokers end their smoking habits.
Avoid Caffeine After Noon
Your body takes 8 hours to break down caffeine. If you have enough in your system when it comes time to sleep, it can prevent you from entering deep sleep or even stop you from falling asleep altogether.
Avoid Alcohol Right Before Sleeping
While alcohol can make it easier to fall asleep, it will actually reduce the quality of your sleep and delay your REM sleep. You may fall asleep faster, but you will likely wake up the next morning without feeling well rested.
It generally takes an average person about an hour to metabolize a single drink. If you have multiple beers, shots, or glasses of wine, you want to finish your last sip with at least one hour per drink before bed.
Staying hydrated can help you flush the alcohol out of your system faster.
Reduce Light Exposure
The light-dark cycle has a huge role in dictating our circadian rhythms.
We want to avoid exposure to bright light close to bedtime. This is especially true with blue light. Blue light suppresses and delays melatonin production. It will trigger awakening processes and confuse our circadian rhythms.
Try to get regular exposure to outdoor light during the day (at least 30 minutes a day.) Direct sunlight right after waking up can help you establish a good circadian rhythm.
Red light has a negligible effect on circadian rhythms. If you are going to use electronics at night, we recommend using software to reduce the blue light from the displays:
If you can’t directly control the screens, you can also use blue light blocking glasses.
Avoid Sleep Disturbance from Pets
According to a poll from the Mayo Clinic Sleep Disorders Center, more than half of people who sleep with their pets surveyed say their pets disturb their sleep.
Dogs can wake you up while they scratch, sniff, or snore. Cats can often be active late at night and early morning hours. If they disturb your sleep, consider keeping them out of your bedroom.
Check Your Posture
Good posture allows for efficient and unobstructed breathing. You want to have good neck and spine alignment while you sleep.
If your neck is extended back or raised, try to use a pillow that compensates lets you sleep in a position with better alignment. If you’re a stomach sleeper, consider using a very flat pillow or sleeping without one. This will help keep your neck and spine straight.
Oversleeping will often leave you feeling unrefreshed and sluggish the next day. It also confuses your internal biological clock for upcoming nights.
After reading this article, you should have a clear understanding about the science behind sleep, how it works, and ways we can sleep better. We have cleared up some common misconceptions behind sleep and explored the importance of good sleep hygiene.
You should now be well equipped with practical ways of regularly getting better rest, and having better performance throughout your day.
This video by It’s Okay To Be Smart has a good overview of what we have discussed on the science of sleep:
Why do we have to sleep? (7:20)
To learn even more about improving your sleep with science, check out the book Sleep Smarter by Shawn Stevenson