Effect Measure

The value of a good night’s sleep

Getting a good night’s sleep is supposed to boost your resistance so you don’t get sick as easily. Or put another way, not getting enough sleep puts you at risk of colds and other nuisance infectious diseases. Is this just an old wives’ tale? Apparently not. Or at least, now we can say there’s some evidence to back it up:.

BACKGROUND: Sleep quality is thought to be an important predictor of immunity and, in turn, susceptibility to the common cold. This article examines whether sleep duration and efficiency in the weeks preceding viral exposure are associated with cold susceptibility. METHODS: A total of 153 healthy men and women (age range, 21-55 years) volunteered to participate in the study. For 14 consecutive days, they reported their sleep duration and sleep efficiency (percentage of time in bed actually asleep) for the previous night and whether they felt rested. Average scores for each sleep variable were calculated over the 14-day baseline. Subsequently, participants were quarantined, administered nasal drops containing a rhinovirus, and monitored for the development of a clinical cold (infection in the presence of objective signs of illness) on the day before and for 5 days after exposure. RESULTS: There was a graded association with average sleep duration: participants with less than 7 hours of sleep were 2.94 times (95% confidence interval [CI], 1.18-7.30) more likely to develop a cold than those with 8 hours or more of sleep. The association with sleep efficiency was also graded: participants with less than 92% efficiency were 5.50 times (95% CI, 2.08-14.48) more likely to develop a cold than those with 98% or more efficiency. These relationships could not be explained by differences in prechallenge virus-specific antibody titers, demographics, season of the year, body mass, socioeconomic status, psychological variables, or health practices. The percentage of days feeling rested was not associated with colds. CONCLUSION: Poorer sleep efficiency and shorter sleep duration in the weeks preceding exposure to a rhinovirus were associated with lower resistance to illness. (Cohen S, Doyle WJ, Alper CM, Janicki-Deverts D, Turner RB, “Sleep habits and susceptibility to the common cold,” Arch Intern Med. 2009 Jan 12;169(1):62-7 [Abstract]; h/t Microbiologybytes)

This is a pretty convincing experimental result showing that adults who report lesser duration or less “efficient” sleep more easily develop cold symptoms after intranasal inoculation with rhinovirus. What does this mean? It could well mean that more sleep protects against disease (or less sleep makes you more susceptible), presumably acting through the immune system. We know there are many connections between the nervous system and the immune system, although the mechanisms are poorly understood. Assuming the association is real and not the result of some hidden bias or chance (less likely, given the size of the effect), we don’t know if it is strong enough to protect against (or sufficient to produce increased susceptibility) for other viruses. But it could also mean that people who are more susceptible also sleep less well, that is, poor sleep is a marker for susceptibility, not the cause. Since we don’t know the mechanism we can’t yet predict if using sleeping medication, say, would be beneficial.

Like all research, this opens up other questions, some less easy to answer. This is the kind of experiment you can do with a relatively benign virus like a rhinovirus but not with influenza or some nastier bug. Meanwhile, I recommend a hot toddy to protect yourself against colds. I don’t have any empirical evidence to cite, but I’m willing to volunteer to study the therapy

Comments

  1. #1 Edmund
    January 29, 2009

    Possibly of interest here: “upper respiratory infection” is listed as a common side effect of Ambien.

  2. #2 biologist
    January 29, 2009

    In the 1980s, a series of experiments conducted in the laboratory of A. Rechtschaffen demonstrated that long-term sleep deprivation in rats resulted in many abnormalities and eventually death. Subsequent work by C. Everson showed that in such rats, bacteria invade body tissues where they are normally not present, and other work by Everson and others has demonstrated immune dysregulation due to sleep deprivation in animals and humans.

    Thus, this new paper expands on a substantial literature exploring the detrimental effects of sleep deprivation on immune system function. While it is certainly possible that people who are more susceptible to rhinovirus sleep more poorly than others, there is substantial evidence to suggest that sleeping poorly in and of itself causes susceptibility to illness.

  3. #3 Lea
    January 29, 2009

    YES WE CAN(NABIS) is the better choice for a good night’s sleep.

    American’s Top Political Priority: Mariquana Law Reform !

    January 16th,2009 By:Allen St. Pierre,NORML Executive Director

    Thanks to everyone who voted in change.org’s “Ideas for change in America” competition. Out of 7,847 ideas generated, “Legalize the Medicinal and Recreational Use of Marijuana” was voted the #1 idea for change (with 19,530 votes) in America!
    Now its time to direct our strong commitment for marijuana law reform at Obama’s official website, where “ending marijuana prohibition” continues to remain in first place…

    http://blog.norml.org/2009/01/16/americans-top-political-priority-marijuana-law-reform/

    **********************

  4. #4 daedalus2u
    January 29, 2009

    My suggestion is that it is due to nitric oxide. The nasal passages are a major source of NO, with the stagnation NO concentration (the level produced if you block air flow through the nose) of 20 ppm (yes, ppm, not ppb). That NO does attenuate many viruses.

    Cold, dry air inhibits that NO production and may be part of why there is an association of heart attacks with cold weather.

    Sleep is a high NO state. Inhibiting nitric oxide synthase inhibits sleep. The usual response to infection is to increase NO levels by expression of iNOS. This has the effect of increasing ATP levels in cells (NO regulates ATP via sGC), and higher levels of ATP increase the rate of turnover of cellular contents via autophagy. Every normal constituent of a cell (except the nuclear DNA) can be replaced by de novo synthesis. All parasitic and infectious components can’t be. Clearing out intracellular infections (TB, Lyme, etc) require high ATP levels.

    Not exactly sure where these particular viruses end up on that scale, but more NO and more ATP is probably better for the humans cells than for the virus.

  5. #5 g336
    January 30, 2009

    Have you noticed, in recent years, the proliferation of ads (particularly on AM radio) for mattresses? The theme goes like this: You’re tired during the day because you’re not getting a good night’s sleep. The reason you’re not getting a good night’s sleep is because you’re *tossing and turning.* And the reason you’re tossing and turning is because you have an old worn-out mattress. Therefore: buy our mattress and you won’t toss & turn, and you’ll get a good night’s sleep and feel rested.

    Wrong diagnosis (tossing & turning), wrong cure (new mattress), but consistent with the corporate mentality of profiting from problems rather than truly fixing them.

    Americans get on average 6-1/2 hours’ sleep each night. Sleep deficit is right up there with stress in terms of health issues that get brushed under the rug in the name of productivity and the work-too-much-and-consume-too-much lifestyle. And it would not surprise me if sleep deficit and stress were actually the leading causes of preventable deaths in the US.

    It would be interesting to compare average nightly sleep duration with longevity for as many countries as the data exist. Anyone know where to start on this?

  6. #6 biologist
    January 30, 2009

    g336,

    I’ve been amused by all the mattress ads, too. But not by the sleeping pill ads. Because, to respond to your question about looking at lifespan vs. sleep duration, it’s been done – and the answer is, 7 hours of sleep at night gives the optimal life expectancy. And more sleep is a lot worse than less sleep, which has little effect statistically. Of course, there are a few caveats – e.g., that people who sleep more may be sicker, and have problems like sleep apnea or whatever, so that in fact it might not be sleeping more that’s really bad per se, etc. But, the evidence is in: America does not have a massive sleep debt.

    See, for instance, the work of DF Kripke:

    Long sleep and mortality: rationale for sleep restriction.
    Youngstedt SD, Kripke DF.
    Sleep Med Rev. 2004 Jun;8(3):159-74. Review.

    Mortality associated with sleep duration and insomnia.
    Kripke DF, Garfinkel L, Wingard DL, Klauber MR, Marler MR.
    Arch Gen Psychiatry. 2002 Feb;59(2):131-6.

    So where does this idea that people have a big sleep deficit come from? I can think of 2 sources. One is that many of us simply feel that we don’t get enough sleep, for one reason or another – kids, work, insomnia, etc. The second reason is that there has been a great deal of propaganda to this effect in recent years that has been propagated through the media. Where did this “information” originate? The source is almost invariably the National Sleep Foundation – which receives its support almost entirely from pharmaceutical companies that manufacture sleeping pills. The NSF has a large stake in spreading the idea that Americans don’t sleep enough, and they’ve done their job well, and contrary to the available evidence. In fact, the evidence is that sleeping pills themselves increase mortality – see, e.g., the 2002 Kripke paper cited above, although that paper was only able to examine the effects of older hypnotics. There is not much reason to believe the newer sleep drugs would be much different in this respect, though; they pretty much act on the same receptors in the brain.

    The evidence is very strong that sleeping 7 hours – or less – is just fine for all of us, even if we feel like we wish we had more sleep. Sleeping less doesn’t kill – but sleeping pills can.

    To add a little speculation: it could be that sleeping a touch less than makes us feel perfectly rested is beneficial to us by inducing sleep-deprivation response programs in the brain (and possibly body), activating the transcription of genes whose corresponding proteins do us good. In many organisms, a little “stress” of one kind or another promotes longevity. That might be true for a little sleep deprivation as well.

  7. #7 anon
    February 2, 2009

    Small quibble, Revere. That Arch Int Med acticle wasn’t really an ‘experiment’. Probably more of an interventional cohort. There are some older experiments showing immune function reduction after sleep deprivation/restriction in conjunction with vaccination which are quite fascinating.

    The other problem with all of this stuff is that almost all of it is based on self-reported sleep duration which is utterly unreliable. It’s as much a psychological variable as it is a biological one.

    So, Biologist, you might want to revise your statements about sleeping less than 7 hours a night being harmless since practically all of the evidence contradicts you, even the forthcoming cohort studies with objective measurements of sleep duration. The experiments don’t obviously indicate a causal link with death but they do show that small amounts of sleep restriction cause detrimental psychological, performance, and physiological changes that are consistent with the establishment of diseases of major public health significance (including probably car crashes).

    As for the National Sleep Foundation being some sort of pharmashill organisation… The press releases might come from them but the research is real. It’s their job to publicize the importance of sleep. They are taking industry support but they do not accept funding from those sources unless it is unrestrictedd (i.e. no string attached).

  8. #8 revere
    February 2, 2009

    anon: I’m calling it an experiment because the investigators controlled the exposure variable. But I acknowledge your point. If one considers the sleep to be the independent variable then interventional cohort is an apt designation.

  9. #9 anon
    February 2, 2009

    That’s a fair stance. I do like the study though. It’s very clever.

    The nature of my work means I have to be fairly exact about study design. Cohort might be one designation but I would also call it quasi-experimental since the intervention is given to everybody.

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