Tuesday, September 06, 2011


Sleep, that part of our life cycle, when we lose contact with the world until we are awaken, and sometimes rudely. For a long time, many have felt that when we sleep, everything stops and we rest our body. Maybe some also think that our body stops functioning for us to rest. Well, the latter is certainly not true, and the formerly is only partly true. It appears that with more and more research, we now discover that when we sleep, part of the body rest, and whine down, but some other part of the body is still very active. This is almost like fat cells around our middle kingdom. It is not an inactive organ, but a very active metabolic, neuro-hormonal organ.
The latest online edition of Hypertension, carries an interesting article by Dr Maple Fung from San Diego, and Dr Susan Redline from Women and Bringham, Boston. It is an interesting study. They have a project called the Outcome of sleep disorders in Oldermen Study. They enrolled 784 men from 2003-2005. Measured their sleep duration, sleep breathing patterns and also their sleep architecture. These are all healthy oldermen with no heart disease or hypertension. They fill up a questionaire, or their health status. After 3.5 years, from 2007-2009, they fill in a second questionaire about their health status, and also undergo another sleep study, on their sleep duration, sleep breathing patterns and sleep architecture.
What they discover was that oldermen who had a shorten duration of "slow wave sleep ( SWS ), had a 2x increase incidence of hypertension after 3.5 years. Interesting. These men had no difference in their overall sleep duration, no difference in their sleep breathing patterns ( no sleep apnea ), and no difference in their REM ( Rapid eye movement ) sleep.
I suppose, I should have began by explaining that when we sleep, our sleep is divided into REM sleep and non-REM sleep. The non-REM sleep phase is further divided into the N1, N2, N3 phase. The N3 phase is also called the SWS phase. This is the phase when it is most difficult to arouse us ( commonly called deep sleep ). It appears that during this phase of SWS ( deep sleep ), the body rest and all our daily metabolic, neuro-hormonal processes wind down and goes to basal level. An inability to get enough SWS does not allow the body to wind down completely, and so the metabolic and neuro-hormonal reactions continue, the sympathetic system and the vagal system continues in overdrive, and these increases the incidence of diabetes and also hypertension.
So sleep like diet and physical activity is important for good health, particularly in oldermen.

No comments: