Mar 192013

Daily Update 4.5

Week 8: Module 4: Date 3/19/13

What is more important than food to the body?  Well, at least AS important? SLEEP!!! As you probably already know the crew is rowing 24 hours a day, in shifts of one, two and four hours. This leaves a schedule of sleep that leaves just one four hour block a day for uninterrupted sleep. This is very different than what most of us are accustomed to. Most of us sleep at night for around 8 hours and if we are lucky wake up feeling rested. Sleep is a highly studied subject although still not fully understood.


Sleep consists of five stages, 1-4 and REM (Rapid Eye Movement). This is an example of a typical night sleep for an average adult.sleep graph

Stage 1 sleep is a very light sleep, from which we can be awakened easily. During this stage people often experience sudden muscle contractions, which are often preceded by the feeling of falling.  In stage 2 our eye movement stops and our brain waves slow.  In stage 3 extremely slow brain waves occur, intermingled with occasional smaller faster waves. Stage 4 consists almost entirely of slow waves and together with stage 3, this is called deep sleep. It is difficult to wake someone from this deep sleep. During these stages there is no muscle or eye movement. When you are woken from this stage you often feel groggy or disoriented. The final stage, REM, is characterized by rapid jerky eye movements in all directions. Our limbs become paralyzed, breathing is more rapid, irregular and shallow, our heart rate increases as does our blood pressure.  It is during this stage that we have dreams.

Image retrieved from

Image retrieved from

While many scientists have different ideas about these stages including REM most agree that going through all of these stages is an important part of sleep.

If you look back to the graph of the sleep cycles you can see that during an average night’s sleep you will go through 4-5 cycles. The later stages of sleep consist of mainly stage 2 and REM.  Again, while the significance of this is yet to be fully understood, the importance is not.  Tomorrow we will look at circadian rhythms and how they influence sleep.



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