Sleep Cycles A Brief Look, for centuries, scientists took sleep as a passive state where the body, along with the brain, would turn off and go into a state of inactivity. The commonly understood reason was supposed to be rest and rebooting the body and the mind. Scientists found that during every sleep cycle, a human brain passed through various stages where the brain is sometimes active, and sometimes it goes into a relaxed or non-responsive state. Based on these facts and the different patterns observed, one can make the right adjustments and improve his sleep.
Sleep cycles are a fundamental requirement that our body needs to fulfill in order to perform properly. Otherwise, we will be performing like devices in dead batteries. Nature has designed our routine in such a way that sleep is inevitable. For that reason, nature has fitted two communicating systems inside our bodies that control and adjust our sleep. One is the sleep-wake homeostat, and the other is our internal biological clock or as well call it, the body clock. Both of these systems are responsible for controlling when we sleep and when we get up. The interesting query remains how do our body and mind transition from sleep to wakefulness and vice versa. Let’s try to figure out.
It was not before the 1920s that scientists had firm beliefs that when our sleep cycle begins, or when we fall asleep, our mind is no longer awake, and it enters a state of rest. Any input from the environment in the forms of signals is not registered because the brain enters into a state of hibernation for a limited amount of time and restart again in the morning. This was a belief that was carried on for a very long time until EEG (electroencephalogram) was invented in 1929.
Electroencephalogram – EEG
The EEG was a revolutionary invention as it allowed the scientists to see what the brain’s internal activities were like when it was in the state of sleep. The first discovery was of sleep cycles that would indicate the level of awareness of the brain to its environment when it sleeps. At times, a brain was found to be more active than at other times.
Detailed researches were conducted, and it was found that electrical signals are generated in the brain while the body is sleeping. These signals end up producing movements in the body muscles and eyes. All the extracted data was then separated into two main categories, which mostly dealt with sleep cycles in REM sleep (rapid eye movement) and NREM sleep (non-rapid eye movement) sleep.
Sleep Cycles What is rem
Rapid Eye Movement Sleep (REM) Normally, the REM sleep is referred to as active sleep, where high frequency and low amplitude waves are observed. There is also a concept of a relation between dreams and the eyes’ movements. Dreamers have been found to have REM sleep and that their dreams are quite clearly remembered and vivid. When a person is dreaming in REM sleep, his body muscles seem to have been paralyzed temporarily so that the person does not act out what he is actually experiencing in the dreams.
Non-Rapid Eye Movement Sleep (NREM) Those people who experience NREM sleep cycles are less likely to experience dreaming as compared to their counterparts. This sleep can be further divided into 3 sleep stages or sleep cycles. N1, N2, and N3. The brain waves in N1 are slow, more synchronized with the eyes showing almost no movement. As we move up and pass through N2 to N3, we experience low frequency and high amplitude waves having spindles. This sleeping stage is called “deep sleep” or “slow-wave” sleep.
When a healthy adult falls asleep, he goes through a series of sleep cycles until he wakes back up. At first, rhythmic and clear alpha activity is observed, having signals of mixed frequency and low voltage. The person starts to nod off and enters the N1 cycle in a duration of seconds to minutes. This transition is mostly with a slow eye movement.
After spending about 1 to 7 minutes in the first sleep cycle, the person moves on to N2 and can stay there for a duration of about ten to twenty-five minutes. Spindle representation with K complexes can be observed here in the recording from EEG equipment.
When the transition from N2 to N3 begins, the high voltage signals with slower wave activities are observed on the EEG equipment. The duration of this sleep cycle is around twenty to forty minutes, and this stage has got many names like “deep sleep,” “delta sleep,” or “slow-wave sleep”. This is a stage where the response rate of the brain to external signals is reduced, and the person goes into his rabbit sleep or, as we call it, falls into a deep slumber. As a result, the person is difficult to wake up.
Different Sleeping Patterns
According to Dr. Thomas Scammell, sleep cycles of NREM and REM occur in every adult’s sleep. Lighter NREM sleep cycles are usually observed with escalating signals in body movements while a person is in the N3 stage. Normally, the first sleep cycle of REM is preceded by N2 of about five to ten minutes. In totality, around 25 minutes of sleep are taken up by REM.
Both the sleep types od REM and NREM take turns throughout the night in an adult’s sleep. A night’s first part is taken by the NREM sleep, where slow-wave occurrences happen. Then the REM sleep cycles take turns. Their first phase can last until 5 minutes from a single minute, and the latter sleep cycles can increase in duration.
The N3 sleep cycle is the longest for the first time, and then it decreases in its duration as it takes turns. It can even be found completely absent from the sleep patterns altogether.
The sleep cycle between REM and NREM can be anywhere from 70 minutes to 100 minutes, whereas an average duration of 90 minutes to 2 hours has been recorded for the later sleep cycles. The sleep cycles are pretty consistent when it comes to duration, and the reason is yet to be discovered.
Another speculation is that mental and physical relaxation is optimized in these sleep cycles, along with an effect on memory and dream. However, this is still speculation, and research needs to be conducted.
Changing Sleep Patterns
Sleep patterns and sleep cycles are affected by so many factors that are always changing in our surroundings. The following factors can be taken into consideration for a better understanding.
- Changing age
- Duration of last sleep session
- Duration of last awake session
- Internal clock
- Body chemical secretions
- Surrounding temperature
- Light in the surrounding
- Stress in personal or professional life
- Physical condition, and so many others.
Even the time of the year can also have an effect on the transition of your sleep cycles and sleep patterns. You might start your calendar year with a REM state and change as the year moves on.
Babies have a duration of 50 minutes to an hour when it comes to shifting from NREM to REM, whereas adults enjoy about one and a half-hour. Children experience the slow-wave sleep cycle more than any other age group, and it decreases as the age increases. A possibility here is taken as the changes observed in the brain’s functionality and structure.
Another very affecting factor is the quality of sleep and the amount of sleep a person has had recently. This factor has been found to be the most affecting sleep cycles and patterns. People often get sleep deprived due to hard work or late night parties and even just for the sake of fun, and this backfires on them by changing their sleep cycles.
Drugs, alcohol, and other such items also have a huge effect on sleep patterns, and they have been found to suppress REM patterns of sleep. The metabolization of alcohol takes place late at night, which triggers REM sleep with consistent waking up. You can do your research on so many other relevant factors for being responsive to change a person’s sleep cycle.
Having a nap at daytime is more common than one thinks. Where the western societies folks prefer to have a long sleep of about 8 hours, there are people who will sleep regularly during the daytime for a few hours.
Both of these patterns have their advantages. Daytime sleep helps you gain your alertness and energy back, and you can continue your day appropriately.
People from the subcontinent and tropical regions have daytime sleep in their regular routine, and they even have their business life designed around it. This practice is so common that the government offices take a break and restore their energy to begin working again.
Afternoon sleep is normally related in such countries with a desire to sleep because a day starts very early. Moreover, when the temperature increases and reaches the maximum at midday, a nap is considered to be the best remedy, which is normally followed by lunch. These periods of sleep are mostly between half an hour and an hour. If the duration exceeds, then it is difficult to wake up because the “deep sleep” mode can get activated.
Experts On Daytime Napping
Many people have reported positive effects of afternoon naps, and they feel lighter and fresher after having their dissipated energy regained. Resultantly, these people can stay up until late at night and still be able to get up early in the morning because their sleep requirements have been met in portions throughout the day.
Experts have a positive review of a daytime nap or an afternoon nap. They believe that this is a good way to regain some lost strength. However, insomniacs should refrain from getting into such sleep cycles. The reason is that they can have their insomnia increased by sleeping in the daytime, which can cause them to lose their sleep completely at night.
Sleep cycles and their effects on human lives have been a topic that is continuously being researched. The effects they cause in our health can be controlled by proper maintenance of our sleep cycles and by trying to make our surroundings as beneficial as possible. With the changing surroundings, we can expect changes in our sleep patterns, and we need to make certain adjustments in order to take advantage of the researches made in this field.