If a Little is Good, is More Better?

Abstract & Commentary

Synopsis: Longer sleep was not associated with increased quality of well-being, but greater sleep
satisfaction was.

Source: Jean-Louis G, et al. Sleep. 2000;23:1115-1121.

Jean-louis and colleagues recruited a total of 273 San Diego adults aged 40-64 years by random telephone dialing. Subjects underwent interviews, collection of demographic data, and administration of the Quality of Well-Being (QWB) and Center for Epidemiologic Studies-Depression (CES-D) scales. They also wore wrist actigraphs at home for 3 days to record level of activity and exposure to light. Greater quality of well-being (QWB) was associated with greater sleep satisfaction, younger age, less obesity, non-Hispanic White ethnicity, and greater light exposure. Sleep duration was not associated with QWB. Depression (CES-D) scores correlated positively with QWB and negatively with self-rated sleep satisfaction and habitual sleep time.

Comment by Barbara A. Phillips, MD, MSPH

As a result of the development of electricity and the 24-hour society, we may be getting only about three-fourths as much sleep as did Americans of the last century.1 Citing numerous publications decrying the reduction of sleep since the development of electricity,2-4 these seasoned sleep epidemiologists set out to learn if America’s rampant sleep deprivation is affecting well-being. They found that it did not, at least in this middle-aged, sun-exposed population who reported sleeping an average of about 7 hours per night. I chose this paper, not because I believe they are correct (I don’t), but because it addresses a "hot" topic, and because Jean-Louis et al found that satisfaction with sleep was associated with improved quality of life and reduced depression scores.

With regard to sleep deprivation/reduction, it matters a great deal whether sleep is curtailed voluntarily to make way for other activities or because of insomnia. Individuals who have reduced sleep because of insomnia almost invariably report reduced quality of life.4,5 It also matters whether the reduction is acute or chronic, and how severe it is. Acute sleep deprivation adversely affects mood and alertness,6,7 but gradual and moderate sleep reduction may not.8,9

In addition to "soft" variables like depression and quality of life, the effects of reduced sleep on measures such as car wrecks, work performance, and life expectancy are of interest. The sleep community is united in its opposition to sleep reduction in commercial drivers.10,11 There are less clear-cut data on the effects of sleep loss in physicians-in-training.12,13 And life expectancy is actually shorter for those sleeping more than 8 hours than it is for those sleeping less than 7.14,15

What does this mean to you? It is probably more important to ask the patient is he is satisfied with his sleep than how long he sleeps. In fact, if you only have time to ask one question about sleep (and if you ask even 1 question about sleep, you’ll be doing better than most), it should probably be, "Are you satisfied with your sleep?"

References

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3. Pack AI, et al. Accid Anal Prev. 1995;276:769-775.

4. Chevalier H, et al. J Psychopharmacol. 1999;13 (4 Suppl 1):S21-24.

5. Zammit GK, et al. Sleep. 1999;22(Suppl 2):S329-385.

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7. Dinges DF, et al. Sleep. 1997;204:267-277.

8. Friedmann J, et al. Psychophysiology. 1977;14:245-250.

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10. Mitler MM, et al. N Engl J Med. 1997;337:755-761.

11. McCartt AT, et al. Accid Anal Prev. 1996;284:511-517.

12. Nelson CS, et al. J Am Osteopath Assoc. 1995;95(10): 600-603.

13. Holzman IR, Barnett SH. Mt Sinai J Med. 2000;67(2): 136-139.

14. Kripke DF, et al. Arch Gen Psychiatry. 1979;361:103-116.

15. Kripke DF, Assmus JD. Sleep Research Online. 1999;2: 1444.