It is something we can't do without. We spend nearly a third of the day doing it. Yep Sleeping! March is sleep awareness month and March 13, 2020 is World sleep day. I therefore, thought it was timely to write about the all important Zzz's.
Sleep is as critical to our existence as food and water. We feel refreshed and recharged after a good night's sleep. On the other hand, some nights although you were in bed for 10 hours, you might still wake up feeling groggy. That is because it is not only the quantity but also the quality of sleep which matters.
In this day and age where speed is of the essence in everything we do, from fast food, fast cars, fast internet, one thing we can't have is fast sleep. An average adult needs at least 7-9 hours of sleep each night. Sleep plays a critical role in functioning of all the processes in the body including brain, immune function, mood, and disease resistance, and the functioning of heart, and lungs to metabolism. Mounting scientific evidence suggests that chronic lack of sleep, or getting poor quality sleep, is associated with increased risk of disorders such as high blood pressure, heart disease, diabetes, depression, and obesity. Recent findings suggest that sleep plays a housekeeping role that removes toxins in your brain that build up while you are awake.
Stages of sleep
Contrary to what we might believe, sleep is actually a very active process. Sleep is a complex phenomenon and includes several stages through the night. There are two main states in the sleep cycle- Random eye movement (REM) and Non-REM. Non-REM sleep which includes the first three stages ;- relaxed wakefulness, light sleep, deep sleep and REM sleep which is the last stage. These four stages follow each other in a cyclical manner throughout the night.
a) Non-REM sleep is the state in which the brain is relatively inactive and our body is movable. Non-REM is further categorized based on roughly how deep the sleep is (relaxed wakefulness, light sleep and deep sleep) and how difficult it is to wake someone from it.
Relaxed wakefulness :- This is a transition stage between being awake and falling into deeper stages of sleep. It is easy to wake up from this stage. During this stage you are more or less aware of your surroundings, but you become increasingly relaxed as you drift off to sleep. This is the stage when some random illogical thoughts (like falling) and twitches occur. Relaxed wakefulness accounts for approximately 5% of total sleep time. Which means in 8 hours sleep, you'll probably be in this stage for 24 minutes.
Light sleep :- This is a stage of light, regenerating sleep. It is still relatively easy to wake up from this stage of sleep. We spend majority (45–50%) of the night in this stage of sleep. Almost 3.5–4 hours out of 8 hours a night sleep. Light sleep is the stage of rest and recuperation.
Deep sleep :- This stage is the most rejuvenating and restorative sleep stage. During deep sleep, the glymphatic system removes waste, such as neurotoxins and beta-amyloids, from the brain. Deep sleep helps in establishing long term memory. It’s very difficult to wake up from deep sleep. If you've ever woken up feeling tired and groggy in the morning, it is probably because you didn't get enough deep sleep or were woken up in the middle of this stage. The amount of deep sleep declines with age. Older adults often report waking up more often during the night which is linked to the decline of deep sleep. Average healthy adult has 1 to 2 hours of deep sleep per night.
b) REM sleep is so called because during this state our eyes move about underneath our eyelids. The brain activity during REM sleep almost resembles wakefulness. During REM our brain is active but the body is paralyzed, and it is when we have our most vivid dreams. Heart rate and respiration rate are increased during REM. There is more REM sleep later in the night than initial sleep cycles. If you are a night owl and go to bed much later than usual, you may skip the first cycles of sleep (including regenerative deep sleep stages) and even go straight to REM sleep. On an average REM sleep accounts for 20–25% sleep in young adults. So if you sleep for 8 hours, it means you are getting 1.5 to 2 hours of REM sleep per night.
With these different stages we are actually very busy while sleeping. The different stages follow each other in a cyclical pattern. A normal cycle starts from relaxed wakefulness, goes through light sleep to deep sleep and then back up towards REM sleep. The average length of each sleep cycle is 90–110 minutes. So in 8 hours of sleep, you’ll usually go through five of these cycles.
How much sleep is enough?
The amount of sleep a person needs and the sleep patterns change as you age, and it also varies significantly across individuals of the same age. Babies initially sleep as much as 16 to 18 hours per day, which may boost growth and development (especially of the brain). School-age children need about 9-11 hours of sleep and teenagers need 8-10 hours per night. An average adult needs 7-9 hours of sleep a nigh and older adults above 65 years of age need 7-8 hours of sleep.
Take Home: Everyone knows that Zzz's are important. But it is both quality and quantity that matters. If you sleep 10 but still wake up exhausted, you may not be getting enough deep sleep. There are a number of strategies that have shown some promise in terms of improving the quality of sleep. For example, reducing stress, establishing sleep rituals and routines, sleeping in a dark room with curtains down, healthy diet, exercising and meditation.
Cover image: Image courtesy :piqsels.com
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