Stages of Sleep and it’s Importance in Overall Fitness
No matter how good your diet is or how often you exercise, you are sabotaging all your efforts, if you are not getting enough sleep. Sleep is important for brain repair and memory consolidation. You not only need good quantity of sleep but also consistent and quality sleep.
Monitoring Sleep and Waking Up at the Right Time
Your alarm goes off each morning, and every time it sounds, you feel the same grogginess. You can wake up feeling refreshed and it actually has little to do with how many hours of sleep you get. Waking up alert means waking up at the right time when your body is naturally close to being awake on its own. The deeper sleep you are in when your alarm goes off, the worse you feel when you are awoken. Sleep monitoring devices track your natural sleep patterns measuring not only how much you sleep but how well. Some of them also wake you up at the optimal time during a light sleep stage. Sleep tracking is included in most fitness trackers available in the market. The monitored sleep pattern and heart rate data from the sleep tracking devices is transmitted to an app on your Smartphone. The apps not only show your sleep cycles but also recommend ways to you improve your sleep.
Sleep and Brain Activity
The brain comprises of cells called neurons and neurons communicate with each other using changes in electrical impulses. We compute these changes in electrical signals as waves. Brain waves are measured in cycles per seconds or frequency or Hertz (Hz). There are four types of brain waves.
The first is the beta wave, which ranges from 13 to 38 Hz and this is usually associated with people who are awake, aware and usually engaged in solving a mental problem or having conscious thoughts. The second type of brain state is the alpha wave, which ranges from 8 to 13 Hz. In this state, the people are awake, calm, relaxed and not thinking actively. The third one is theta, which ranges from 4 to 8 Hz. This is usually associated with people who are in a state of deep relaxation like hypnosis, mediation or light sleep. The fourth or the slowest brain wave is the delta wave, which is below 4 Hz. This state is associated with deep dreamless sleep.
Many people think that we have one type of brainwave working at one time. However, this is not actually true. We have all the types of brain waves working at all times, but just at different intensities.
What are the Different Stages of Sleep?
Even though you are not conscious during sleep, your brain is deceptively active. It goes through multiple cycles with distinct brain patterns. There are two main stages that your body goes through, while sleeping – Non-REM or Non Rapid Eye Movement stage and REM or Rapid Eye Movement stage. The Non-REM stage is further sub divided into three stages.
N1 Sleep – N1 is the stage between sleep and wakefulness. In this stage, people are generally easy to wake up. This is when your brain starts producing theta waves. You might experience strange sensations, which include hearing and seeing things that are not there. Another common feeling in this stage is the feeling of falling called hypnic jerks or muscle twitches that you sometimes experience as you fall asleep.
N2 Sleep – This is a slightly deeper stage of sleep. People in N2 state are harder to awaken. We see more theta waves as well as something called sleep spindles and K-complexes. Sleep spindles are bursts of rapid rhythmic brain activity that help maintain a tranquil state during sleep. K-complexes are low frequency high amplitude waves and help to keep you asleep by suppressing cortical arousal. This is the state where you spend most of your time sleeping.
N3 Sleep – This stage is often referred to as delta or slow wave sleep because the brain waves are very slow. People in this stage are very difficult to wake up. If someone walks or talks in their sleep, this is the stage where it happens.
In this stage, your eyes move very rapidly beneath your lids and most of your other muscles are in a paralyzed state. REM sleep is sometimes called paradoxical sleep because your brain actually seems very active and awake, but your body is prevented from doing anything. Brain waves in REM stage are predominantly beta and alpha.
In a normal night of uninterrupted sleep, you cycle through these stages about four or five times each. Each cycle can last anywhere from 90 to 120 minutes. The order within a cycle tends to go from N1 to N2 to N3 and then back to N2 before entering REM sleep.
Just like our sleep has cyclical stages, so does our wakefulness and our transition from wakefulness to sleeping. Circadian rhythms are regular body rhythms across a 24-hour period, which is also called our internal biological clock. The circadian rhythm controls our body temperature and sleep cycles. Daylight is a big cue for circadian rhythms and even artificial light can affect your biological clock. These circadian rhythms change as you age. The internal clock is very delicate and does not respond well to big changes to your routine. A sudden upset to your circadian rhythm can cause hormonal regulation to be out of sync as well as your wake sleep patterns and your times of peak productivity. That is why we are so affected by daylight savings time and jet lag. A long term problem with your internal clock can cause serious health issues.
How Much Sleep Do You Need?
Some studies done on large groups of people found that people who slept around seven hours had the lowest mortality rate. These studies found that sleeping too much or too little was associated with worse health. It is important to note that these studies were merely surveys and someone who sleeps seven hours a day probably has a job and access to better healthcare while someone who gets more than nine hours of sleep might be unemployed and depressed.
There is no magic number for the amount of sleep needed to perform at your best. Quality sleep is more important than the number of hours you sleep and the need for sleep is different for different individuals. To personally see if you are getting the right amount of sleep you need to look at several factors. The most obvious is, how best do you feel without excessive amounts of caffeine. If you feel awake throughout the day, you are probably getting enough sleep. If you feel tired all day then you probably need to get more. If you fall asleep within five minutes of going to bed, you are probably sleep deprived.
The Effects of Sleep Deprivation
Sleep deprivation has lasting consequences on brain and body and these consequences can be alarming.
Benefits of Good Night’s Sleep