Posted by Harish at Saturday, May 29, 2010
I must say that before collecting the required information for this post, I did not know that there is so much stuff involved with sleep. The main reason for me to choose this topic is that during exams I observed the difference in attitude, behaviour, alertness, memory, practically everything related to a person getting differed because of the change in sleep pattern. I started to ask so many questions regarding sleep and for some of those, I have found answers. I present them before you here in this post.
What is sleep?
Sleep is a state of suspended activity in our body during which our voluntary actions and muscles are partially or completely unconscious. During this state we are less likely to respond to stimuli. This state is easily reversible compared to coma or hibernation.
Why do we feel sleepy?
Everyday we do a lot of work. Mentally or physically. These generates a hormone called adenosine. The more adenosine we possess in our body, the more sleepy we feel. The amount of adenosine a person is able to hold without drifting to sleep varies from person to person. When the breaking point is reached, the internal clock of our body called circardian clock is signalled. This clock is the internal timekeeping, temperature-fluctuating, enzyme controlling device. Honestly I do not know where this is present in our body but what it does is controlling the enzymes in the body to do various activities like maintaining body temperature, falling asleep etc. So when adenosine has reached the breaking point, this circardian clock tells the body to fall asleep.
What are the benefits of sleep?
During sleep, almost our entire body is at rest. During this time, the growth enzymes are triggered. The muscles restored to full energy and dead cells are treated faster. Besides, the neurons are treated. During this time our memory is organised too. The adenosine accumulated is cleared up. So basically the entire body along with the brain is restored to full working condition.
What happens if I dont get enough sleep?
I guess by now it is obvious what happens due to lack of sleep. Most of the time if we do an excessive night out, we feel nervous, sleepy, tired, less alert, unable to make decisions and memory loss (happens often in the exam hall!). The lesser we sleep, the more sleep debt we accumulate.
How to pay back the sleep debt?
When the debt is small you can pay it back by having a good weekend's sleep. Don't make this a habit by sleeping less on weekdays and more on weekends as it will lead to more problems like insomnia. When the debt is large, you might consider taking a sleep vacation. Take a few days off and sleep as much as you can. It might sound ridiculous at first but it really works and after that you'll feel very fresh and energetic.
How much sleep is adequate?
This one is pretty standard and easy to find answer to.
New born – Upto 18 hours
1 to 12 months – 14 to 18 hours
1 to 3 years – 12 to 15 hours
3 to 5 years – 11 to 13 hours
5 to 12 years – 9 to 11 hours
Adolescents – 9 to 10 hours
Adults and elderly – 7 to 8 hours
What happens during sleep?
During sleep we undergo various stages of sleep. They are as follows.
Stage N1: This is the starting stage. The inital time when our eyes move slowly under the eyelids. Musles loosen up. From this stage we can be awaken easily. Usually this lasts for a maximum of ten minutes .
Stage N2: The eye movements stop. Heart rate slows down and our body temperature decreases. This marks the beginning of sleep.
Stage N3: This is the deep sleep phase. Usually lasts a maximum of 70 minutes in the night time and less during dawn and day time. It is tough to awaken a person from this stage. This is the stage of muscular recovery. Blood flow and brain activity decreases and more of the restoration work is done on the other muscles of the body. This is why when you are awaken suddenly from this stage of sleep you feel groggy with a severe headache because blood takes a while to enter the brain and for brain to get back into full action.
REM Stage: This phase is characterised by Rapid Eye Movement and hence the name REM. During this stage, the restoration is concentrated on the brain. So less blood flows to the other parts, the brain cells and neurons are restored. During the restoration of neurons, they organise the memory. This is why we get dreams. This stage of lesser duration during night and may extend upto 70 minutes during dawn and morning time sleep. That explains why we are able to remember the dreams which happen in early morning and just before we wake up mostly.
These four stages constitute a sleep cycle as follows N1 -> N2 -> N3 -> N2 -> REM. The entire sleep cycle lasts for around 90 minutes. So whenever you are sleeping, try to sleep in multiples of 90 minutes to let the cycle complete properly and hence an efficient sleep.
How do we know if we have enough sleep?
If you dont sleep immediately after falling down on the pillow and get up without using an alarm clock, you are having adequate sleep.
How to get better sleep?
The things which affect sleep are stress, pain, illness, drugs, illness, lack of regular sleep schedule or an uncomfortable environment. Avoiding these will give us a good sleep.
Sleep is one thing which we humans are not able to fully understand and appreciate. Lots of research is happening in this field. So whatever information that I have presented here in this post is with regards to the present time. In future, these ideas may be further developed into a mature understanding of sleep.