Is sleep being elusive? Are you wondering why you don’t get to sleep longer even on weekends? Are you tired of hearing your friends brag about their restful slumber? If your answer is yes to just one of these questions, then be ready for what we have in store for you!
When going to bed on a work week, no matter how early or late it is, we still tend to calculate how many hours of sleep we would probably get before hearing the annoying sound of our alarms. Even if we go to bed early, restful sleep is still not guaranteed. Most of the time, we lie awake staring at the ceiling. Sometimes, we go back to browsing our phones, looking for nothing in particular until our eyes get tired or sleepiness finally kicks in.
We’re already used to getting less and less sleep as we grow older, but is there a way to change that? Of course, there is – or should we say, ‘there are’! Before we go there, let’s first learn how sleep works and why we desperately need it.
The National Institute of General Medical Sciences defines circadian rhythms, also known as circadian cycles, as the “physical, mental, and behavioral changes that follow a 24-hour cycle”. In another words, circadian rhythms are the natural process in which our bodies respond to light and dark environment. This affects all living things, the reason why we are (or should be) asleep at night and awake when the sun is up.
Here’s an example of an average circadian cycle of a teenager, starting from when sleep is initiated:
- 11:00 PM – Getting Sleepy. This is the time when Melatonin, known as the ‘sleep hormone’, kicks in. In adults, melatonin kicks in an hour early (so around 10:00 PM). It is imperative that no gadgets should be used during this time because the blue light from the screens can suppress the sleep hormone and therefore disrupts the circadian cycle.
- 3:00 AM to 7:00 AM – dubbed as “The big dip”, this is when the energy is at its lowest, probably the deepest sleep in the cycle.
- 10:00 AM to 1:00 PM – After waking up at around 9:00 AM to 10:00 AM, energy picks up in this stage because our body temperature naturally rises throughout the morning therefore increasing our alertness and sharpness.
- 2:00 PM to 5:00 PM – described as the “afternoon slump”, this is when you might crave a snack and just choose to sit around since your energy is dipping. In adults, the energy dips an hour earlier – from 1:00 PM to 3:00 PM.
Changes in our bodies, sleeping habits, and environmental factors (even changes in our work shifts) can usually cause our circadian rhythms to be out of sync. These changes bring about the problems we have such as insomnia and other sleep disorders. These sleep disorders can lead to chronic health conditions such as depression, diabetes, obesity, bipolar and seasonal affective disorder.
Stages of Sleep
Sleep depends particularly in every person; it is different in each of us. Our total sleep is comprised of several rounds of the sleep cycle, which in turn is composed of four individual stages. Sleep cycles change normally as we progress through our nightly slumber. It usually varies from person to person and night to night based on different factors such as age, sleep patterns (daytime napping!), and – believe it or not – alcohol consumption.
Sleep has two basic types – rapid eye movement and non-rapid eye movement. The four stages of sleep are classified into these types and determined based on our brain activity during sleep.
The American Academy of Sleep Medicine classified and defined the four sleep stages as the following:
Stage 1: non-rapid eye movement type (N1). Also known as the “dozing off” stage, normally lasts from 1 minute to five minutes only.
During this stage, our body has not fully relaxed yet but, together with our brain, both activities start to “slow with periods of brief movements” – commonly known as twitches. It is still easy to wake us up during this sleep stage, but if we are not woken up of disturbed, it can quickly lead into stage 2.
Stage 2: non-rapid eye movement type (N2). In this sleep stage, our body enters to a “more subdued state” which includes relaxed muscles, drop in temperature, slowed heart rate and breathing. Also, our brain waves show a new pattern and the eye movement stops. Although our brain activity slows fully, there are still short bursts of activity that helps in resisting being woken up by anything in the external environment.
Stage 2 usually lasts for 10 to 25 minutes during its first cycle, and during the night, each N2 stage can become longer. Typically, we spend half our sleep time in this sleep stage.
Stage 3: non-rapid eye movement type (N3). Also known as the “deep sleep”. In this phase, it is harder to wake us up. Our body relaxes even further and our pulse, muscle tone, and breathing rate decrease. Our brain activity in this period starts to have an identifiable pattern know as delta waves.
Many experts agree that this stage is very critical to restorative sleep – it allows for bodily recovery and growth. It can also bolster our immune system and other essential bodily processes. Even though our brain activity is proven to be reduced during this stage, may evidences suggest that deep sleep contributes to creativity, memory, and insightful thinking.
We normally spend the first half of the night mostly in deep sleep. But in the early sleep cycles, this stage usually lasts for only 20 to 40 minutes.
Rapid Eye Movement (REM) Sleep. As we continue sleeping, the first three non-rapid eye movement sleep stages get shorter and shorter. Moving forward, more and more time are spent in REM sleep. Durig this stage, our brain activity picks up – close to the levels of being awake. At the same time, our muscles experience temporary paralysis, also known as atonia, but our eyes are still moving and breathing still continues.
This sleep stage is believed to be very important to cognitive functions such as learning, creativity, and memory. Also, this stage is known for the most vivid dreams, probably because of the uptick in brain activity. Dreams may be occurring in any sleep stage but they are surely less common in the non-rapid eye movement sleep stages.
Normally, we don’t enter this sleep stage until we have been asleep for about 90 minutes. As the night progresses, REM sleep stages get longer particularly in the second half of the night. REM sleep stage may only last a few minutes in its earlier stages but it can last for about an hour in its later stages. In adults, REM stages comprises around 25% of our total sleep.
Sleep and Exercise
Experts agree that the relationship between sleep and exercise is reciprocal. To simply put it, many people find it easier to sleep when they have exercised, and it is definitely easier to work out after having a good night’s sleep. But how exactly is the relationship reciprocal? Let’s dig into the specifics.
On Exercise Affecting Sleep
Some researchers have identified the exact effect of exercise on sleep. In particular, exercise improves sleep quality. It is said to increase the overall amount of time we spend sleeping as well as the amount of time we spend in deep sleep (stage 3). As we already know, deep sleep is also restorative sleep, our body basically repairs itself during this stage.
Moreover, exercise is believed to also provide significant stress relief which is surprisingly associated with sleep troubles. According to studies, nearly half of adults expressed that stressful thoughts keep them awake at night. During exercise, our brain releases endorphins – chemicals that give us that post-exercise high, boosting our mood and reducing stress at the same time.
On Sleep Affecting Exercise
Studies show that people who experience restless or insufficient sleep and those with sleep disorders tend to be less active than their peers who sleep well. This might be because the symptoms of such sleep disorders including fatigue, low energy, and daytime sleepiness make it more challenging to get the motivation to work out.
Not getting a good sleep is also a prelude for low activity levels. Even just one night of poor sleep can already lead people to cut their workouts short. More than that, studies have shown that people who experience poor sleep often could become less physically active in the next two to seven years.
On the other hand, better sleep leads to beneficial workout routines. Multiple studies have shown that athletes who get more sleep have improved their performance and lowered their risk of injury and illness. A study involving Stanford University men’s basketball team have shown that improved sleep lead improved shooting accuracy and sprint times.
Where to start?
If you are already working out, then good for you! All you need to do is be consistent in going to the gym or hitting the tracks. Most of us adults need an average of 8 hours sleep every night. However, if we frequently exercise and strain our muscles, we would need more than 8 hours of sleep to make sure our body properly recovers. To know more about sleep tracking, you read about it here.
If you’re just about to start, or planning to live a healthy lifestyle, it is best to start with aerobic exercise. Some studies have found that a short 30-minute session of moderate intensity aerobic exercise can already improve sleep come that night. In a study conducted involving individuals with obstructive sleep apnea, researchers have found that moderate intensity aerobic exercise and resistance training reduced their symptoms by a quarter. It has also relieved other symptoms such as depression, fatigue, and daytime sleepiness.