Yet another reason for a good night's sleep

How much do you sleep at night?

If you’re like most of the people I know, the answer is “not enough”. There’s a reason Starbucks coffee shops are popping up literally meters away from one another. Everybody has a reason to be sleep-deprived: new kid, big job, World of Warcraft, etc. So what if we’re cutting the night short a few hours? Other than the need for an overpriced coffee (or two, or three), it should be just fine, right?

Maybe not, if you believe the latest research on sleep and Alzheimer’s disease.

Alzheimer’s disease, a debilitating form of memory loss and cognitive decline, is the most common form of dementia. It is thought to be caused at least in part by amyloid beta (A-beta), a peptide (short protein). Your brain cells (neurons) normally make some A-beta. The problem that arises with Alzheimer’s disease is that neurons make too much A-beta, and these molecules aggregate together in chunks. It’s those A-beta chunks that are toxic, and their formation is concentration-dependent, which means the more A-beta you have floating around, the higher the probability of toxic chunks forming.

The recent article published in the journal Science looks at levels of A-beta in the brains of normal mice and in the brains of a mouse model of Alzheimer’s disease. The researchers studied the mice when they were 3 months of age, so well before big deposits and chunks of A-beta start occurring.

The interesting finding of this study is that the levels of A-beta in the brains of both types of mice were significantly correlated with the amount of time they spent awake. More time spent awake lead to more A-beta. Because the control, normal mice also exhibited this relationship, it means that it is not linked to the disease. It’s just a normal fluctuation of A-beta levels linked to the sleep-wake cycle. To be certain this link was relevant for human physiology, they also tested this in healthy humans and, sure enough, they observed the same correlation.

Not surprisingly, when the researchers proceeded to sleep-deprive the mice, they showed an even larger increase in A-beta levels. This increase was also observed when the mice were given a drug that promotes wakefulness (don’t extrapolate this to coffee just yet… But maybe keep it in mind…). The study also points out that the Alzheimer mice who are sleep-deprived showed much greater numbers of A-beta chunks (the toxic stuff) compared with non sleep-deprived mice.

If you come to Scientific Chick for relevant findings, this one is for you. The study essentially implies that optimizing sleep time could potentially inhibit the formation of chunks of toxic A-beta and slow the progression of Alzheimer’s disease.

We all know that Alzheimer’s disease is terrible, and that sleeping in is glorious. Let’s just put two and two together, shall we? Easier said than done, I know…

Mr. Minou gave up on caloric restriction but approves of this new approach to ward off age-related diseases.

Reference : Amyloid-{beta} dynamics are regulated by orexin and the sleep-wake cycle. (2009) Kang JE, Lim MM, Bateman RJ, Lee JJ, Smyth LP, Cirrito JR, Fujiki N, Nishino S, Holtzman DM. Science Sep 24. [Epub ahead of print]