Whilst the topic of sleep is so broad, we thought we would look into some basic information on a subject matter extremely important to optimal functioning.
Sleep is important because it is an active period in which a lot of essential processing, restoration, and strengthening occurs.
Stages of sleep
During sleep, we usually pass through five phases of sleep: stages 1, 2, 3, 4, and REM (rapid eye movement) sleep. These stages progress in a cycle from stage 1 to REM sleep, then the cycle starts over again with stage 1. We spend almost 50 percent of our total sleep time in stage 2 sleep, about 20 percent in REM sleep, and the remaining 30 percent in the other stages. Infants, by contrast, spend about half of their sleep time in REM sleep.
Stage 1 (light sleep) - We drift in and out of sleep and can be awakened easily. Our eyes move very slowly and muscle activity slows. People awakened from stage 1 sleep often remember fragmented visual images. Many also experience sudden muscle contractions called hypnic myoclonia or hypnic jerks, often preceded by a sensation of starting to fall.
Stage 2 - Eye movements stop and our brain waves (fluctuations of electrical activity that can be measured by electrodes) become slower, with occasional bursts of rapid waves called sleep spindles.
Stage 3 & 4 - In stage 3, extremely slow brain waves called delta waves (electrical activity) begin to appear, interspersed with smaller, faster waves. By stage 4, the brain produces delta waves almost exclusively. It is very difficult to wake someone during stages 3 and 4, which together is called deep sleep. There is no eye movement or muscle activity. People awakened during deep sleep do not adjust immediately and often feel groggy and disoriented for several minutes after they wake up.
REM - When we switch into REM sleep, our breathing becomes more rapid, irregular, and shallow, our eyes jerk rapidly in various directions, and our limb muscles become temporarily paralysed. Our heart rate increases, our blood pressure rises. (I know this sounds like a scene from the exorcism… however, it is extremely important during our sleep cycle).
One of the vital roles of sleep is to help us solidify and consolidate memories. As we go about our day, our brains take in an incredible amount of information. Rather than being directly logged and recorded, these facts and experiences first need to be processed and stored; and many of these steps happen while we sleep. Overnight, bits and pieces of information are transferred from more tentative, short-term memory to stronger, long-term memory—a process called "consolidation." It has been proven that after people sleep, they tend to retain information and perform better on memory tasks. Our bodies all require long periods of sleep in order to restore and rejuvenate, to grow muscle, repair tissue, and synthesize hormones.
Sleep helps maintain a healthy balance of the hormones that make you feel hungry (ghrelin) or full (leptin). When you don't get enough sleep, your level of ghrelin goes up and your level of leptin goes down. This makes you feel hungrier than when you're well-rested.
Sleep also affects how your body reacts to insulin, the hormone that controls your blood glucose (sugar) level. Sleep deficiency results in a higher than normal blood sugar level, which may increase your risk for diabetes.
Sleep also supports healthy growth and development. Deep sleep triggers the body to release the hormone that promotes normal growth in children and teens. This hormone also boosts muscle mass and helps repair cells and tissues in children, teens, and adults. Sleep also plays a role in puberty and fertility.
Your immune system relies on sleep to stay healthy. This system defends your body against foreign or harmful substances. Ongoing sleep deficiency can change the way in which your immune system responds. For example, if you're sleep deficient, you may have trouble fighting common infections.
How Many Hours of Sleep Should We Get??
Healthy sleep is critical for everyone, since we all need to retain information and learn skills to thrive in life. While adults need 7-9 hours of sleep per night, one-year-olds need roughly 11 to 14 hours, school age children between 9 and 11, and teenagers between 8 and 10.
The amount of sleep a person needs also increases if he or she has been deprived of sleep in previous days. Getting too little sleep creates a “sleep debt,” which is much like being overdrawn at a bank. Eventually, your body will demand that the debt be repaid. Our bodies do not seem to adapt to getting less sleep than we need; while we may get used to a sleep-depriving schedule, our judgment, reaction time, and other functions are still impaired.
Things to avoid
While watching TV, checking social media and texting can feel like second nature, especially right before bed, these activities can be quite harmful for your chances of getting a solid night’s sleep. The light emitted by these devices stimulates the brain, making it even harder for you to snooze all night.
Alternative - To unwind, try reading, listening to calming music, or meditating.
Whilst it does vary from person to person depending on their age, weight, gender and overall tolerance, a safe timeframe to give yourself would be at least 6 hours before bedtime to allow the stimulant effect to wear off. However if your tolerance to caffeine is low it is recommended to consume caffeine in the A.M.
Drink lots of water
Whilst we explained in our other article about the benefits of staying hydrated, it is not a good strategy to drink a huge glass of water before bed. Instead, make sure you are drinking plenty of water throughout the day and always be sure to use the bathroom before you head to bed, even if you do not feel like you have to.
People awakened after sleeping more than a few minutes are usually unable to recall the last few minutes before they fell asleep. This sleep-related form of amnesia is the reason people often forget telephone calls or conversations they have had in the middle of the night. It also explains why we often do not remember our alarms ringing in the morning if we go right back to sleep after turning them off.