You’ve no doubt heard about sleep cycles, but what exactly are these phases of unconsciousness, and why are they so important to us? Until the 1950s, sleep was seen as simply a dormant, passive phenomenon. Now though, we know that there is much more to it than this. Our brains are in fact highly active during slumber, and there are distinct stages of unconsciousness that we all experience. This blog will take a look at the various phases of sleep, and examine why they matter.
The initial stages of sleep
It is now known that sleep follows a pattern of alternating rapid eye movement (REM) and non-rapid eye movement (NREM) phases in a cycle that repeats itself around every 90 minutes. NREM is itself subdivided into three stages.
This is the very light sleep that people experience when they first nod off. It’s common to drift in and out of slumber during this stage, and it’s easy to be awakened. Many people experience sudden contractions of their muscles and this is often preceded by the sensation of starting to fall.
During the second stage, people’s eye movements stop and their brain waves begin to slow down. Meanwhile, their breathing and heart rates become regular and their body temperatures drop.
In the third phase, which is referred to as deep sleep, very slow brain waves called delta waves begin to appear, interspersed with smaller, speedier waves. This is the most restorative type of rest, and it sees blood pressure fall, breathing slow down and muscles relax. Also, blood supply to the muscles increases and tissue growth and repair occurs. Another key feature of this stage is the fact that important hormones are released. It is very difficult to wake someone up during this phase. If people are awakened, they do not adjust immediately and they may feel disorientated for a short period of time.
Around a quarter of the night is spent in REM, and this usually first emerges around 90 minutes after individuals nod off. During these phases, people’s breathing becomes more rapid, irregular and shallow, and their eyes move quickly in various directions. Heart rate increases, blood pressure rises and muscles become temporarily paralysed. When individuals wake up during REM, they often remember their dreams.
Complete REM cycles usually last between 90 and 110 minutes. The first sleep cycles contain relatively short periods of REM, and as the night draws on, these phases increase in length. At the same time, deep sleep decreases later into the night. By morning, people spend nearly all of their sleep in stages 1, 2 and REM.
We usually spend more than two hours each night dreaming, yet it’s not yet known exactly why we do this. The renowned psychologist Sigmund Freud believed that this activity provided a ‘safety valve’ for unconscious desires. However, scientists now have other ideas. For example, they have discovered that REM stimulates the areas of the brain that are used in learning. This could mean the sleep phase plays an important role in brain development during infancy.
What rats can teach us
Experts are still trying to get to the bottom of why exactly we need sleep cycles. However, animal studies have shown that they can be necessary for survival. For example, while rats normally live for two to three years, research has demonstrated that when the animals are deprived of REM sleep, they survive for only around five weeks. Meanwhile, when they are deprived of all sleep stages, they live for an average of just three weeks.
Sleep-deprived rats also have abnormally low body temperatures, and they tend to develop sores on their tails and paws too. This may be because their immune systems have become impaired.
The importance of sleep cycles for our health
Whatever the function of sleep cycles, we know that getting a sound night’s slumber that incorporates all of these phases is important. Going through this process helps us to repair and grow our tissues, and it gives us an energy boost for the day ahead. It also contributes to a healthy immune system. Meanwhile, you might be surprised to learn that sleep can help to regulate our appetites by controlling levels of the hormones leptin and ghrelin, which influence our feelings of hunger and fullness.
In addition, sleep plays an important role in helping to ensure our nervous systems function properly. Too little slumber can leave us feeling tired and unable to focus. It can also result in impaired memory and diminished physical performance. Prolonged sleep deprivation can also cause mood disorders and even hallucinations.
Top tips for a better night’s kip
If you’re struggling to get enough rest, you won’t experience the restorative, energy-giving powers of successful sleep cycles. The good news is, there are ways to increase your chances of nodding off at night. First and foremost, make sure you have a comfy bed. Adjustable beds are well worth checking out. These products can be set to your preferred sleeping position, and our versions also come with a relaxing massage function that can help to soothe your aches and pains and put you in the right mood to drift off. Bear in mind that a supportive mattress is a must too.
It also helps to make sure that light and temperature levels in your bedroom are just right, and if you have a snoring partner or a noisy household, try using earplugs at night.
You might benefit from making certain lifestyle changes too. For example, cutting down on caffeine, cigarettes and alcohol can help, and additional exercise could enhance your ability to sleep. Avoid eating meals shortly before bedtime as well, as this can disrupt your slumber.
If possible, try to stick to a routine when it comes to going to bed and getting up too. This will help you to set your body clock.
By following advice like this, you should stand a better chance of resting peacefully at night, and of experiencing the all-important phases of sleep.