It also turns out that changes in sleep patterns can have a profound effect on our lives. A new study, published in Sleep, states that changes in our sleep patterns that we make- or just happen as we age- in our late middle ages can lead to cognitive decline. This decline is equivalent in scope to adding some 4 to 7 years to our actual mental age. Notice, I said “changes” in sleep patterns.
Drs. Ferrie, Shipley, Akbarly, Marmot, Kivimaki, and Singh Manoux, examined the Whitehall data to so determine these facts. For those of you unfamiliar with this study (I certainly was), the study was developed to determine the social determinants of health. Originally, the study only included male British civil servants. The study has now instituted a second phase, involved civil servants aged 35 to 55, 2/3 of whom are men.
The subjects in this study included about 1/2 the total potential population; 5431 participants (1459 women and 3972 men) that were examined at both the 1997-9 and 2003-4 periods of the longitudinal study. However, only four sleep groupings were made: those that increased sleep duration above the original 5-6 hours of the baseline period, those that increased sleep duration from the 7-8 hours baseline, those that decreased sleep from 9 or more hours from the first period, and those that decreased sleep from 6-8 hours from the first period. The data were adjusted for the subjects’ education and occupation positions (although all the subjects were white-collar workers, since they were civil servants). The range in salary demonstrated a 10 fold spread among the included individuals. These factors (education, occupation) are known to affect cognitive performance, in general.
It seems that about 7% of women and almost 9% of men increased their sleep duration from 7-8 hours in the two study periods. The scores for this cohort dropped on 5 of the 6 cognitive function tests (only the verbal memory tests had no changes). Another cohort (comprising 25% of the women, 19% of the men) decreased their sleep duration over the two periods. This cohort demonstrated decreased functionality on 3 of the 6 cognitive tests (excluding the reasoning, vocabulary, and global stati). Those who maintained 7 hours of sleep nightly had among the highest cognitive measures; those sleeping 6 hours were the next higher functioning subset. The outlying periods of sleep (8 hours or more, less than 6 hours) were those that performed poorest of all the cohorts. As you can see, 58% of the men and about 1/2 the women experience no changes in their sleep duration over the 6 year span.
So, now we have a few more pieces of data about sleep patterns. Generally, if we sleep too little, our performance may suffer. (See previous articles on this subject). But, if we sleep too much, our performance suffers even more. The question still remains for the bulk of the population- which sleep duration is better- six (6) or eight (8) hours?
Interesting study, Roy. I sleep between 7 and 8 hours a night. I have always been an early to bed, early to rise person. I am almost always in bed by 10:00 pm and my husband’s alarm goes off at 5:30 am. I usually wake up about that time even if the alarm doesn’t go off.
What about shift workers who have to change their sleep schedule every week or so? My ex did that and I think it really messed him up.
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Hi, Janette:
I could say that is also a function of where you live! Many of my friends used to be night-owls, until they moved to different places (Portland, Seattle), where there is no night life. But, when return to civilization, they are up late to enjoy the capabilities of the area.
Regarding the shift workers, that is combining two different issues. One is the amount of sleep needed. That is what was discussed here. The second issue is the affect on circadian rhythm, which was NOT discussed here. Alterations to circadian rhythms are not well accommodated by the body. For example, if one could survive three hours of sleep every day going to sleep at 3 and arising at 6, and then had to adjust the work hours (to deal with a foreign client, for example), so he now went to sleep at 10 and tried to awake at 1, the 3 hours of sleep will probably not suffice- not because it’s the three hours, but because the body (and the brain) have become “discombobulated” (now, there’s a real technical term 🙂 ).
Like eating Roy, sleep is personal. Studies say but the environment on studies is unreal. Routine matters and so does listening to your body. I need a nap so I think I will go have one. Only slept 6 1/2 hours last night. Need another 30 minutes
I can hear the Z’s around the globe, already, Roberta. Enjoy your rest!
Thanks for your comments.
Roy
Hey,
We had huge discussions on this while doing our Bachelors; while we were studying “Sleep”. When I read about you, you mentioned that you sleep 3 hours and I was like….I have to look into this again, a person who sleeps so less and yet manages to write really interesting and intelligent posts! I will probably have to hire you as a subject while I do more research on this!
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There is data that folks can sleep three hours a night and function perfectly. They (like me) have been doing it a long time- and are about 1/2% of the population, at best. They also know when they, due to physical ailments, are unable to maintain that regimen- and take a nap or go to sleep early. Once the cold or flu or other ailment passes, they resume their schedule. I do think, however, that the data demonstates that it can’t be a rolling schedule. The onset of sleep has to occur at roughly the same time each day (rotating schedules do not work).
Thanks for your comments, Hajra.
Drop in again, soon!
Roy
I am so glad you liked this piece. Thank for visiting and commenting.
Roy