How Much Sleep Should You Be Getting?

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SBB: Should we be waking up at a certain time? Is sleeping in a good idea or a bad idea?

SV: Because sleep is controlled by circadian and homeostatic factors, you absolutely cannot get too much sleep. You can feel sort of that drunken kind of hangovery thing if you sleep in late on weekends, but your body needs that sleep. That tired feeling after sleeping for a long time means you went into deep sleep and you’re still in a sleep inertia phase where you’re not fully kicked out of that sleep.  If you can, you should sleep in. But don’t make a practice of this; sleeping in just means you are not getting enough sleep during the week.

Our research in my lab at Penn really breaks the myth that you can just reduce your sleep time during the week and then catch up on the weekend. Our work in a mouse model does show that the mice will get lasting neural injury and neuron loss in specific groups of neurons with sleep loss. We have to start thinking about sleep differently. The neurons lost include locus coeruleus neurons, which when injured in animal models can exacerbate Alzheimer’s pathology. Thus, it is possible that short sleep early in life could hasten the onset of Alzheimer’s.

Our main goal is to figure out the molecular mechanisms to protect neurons. We have to discover how to provide the best protection for the brain for sustained wakefulness. And I think there will be other interventions that come around the pike where people just figure out how to build in nap time.

SBB: Should we all nap?

SV: It’s unclear. If you nap, you will reduce your homeostatic drive and so your nighttime sleep will be worse. That’s always the gamble. You just have to figure out what works best for you. But if you’re working double shifts and you have a long commute you probably are better off having a two-hour nap here and there.

The real stress on the brain that predicts poor performance, is the amount of time spent awake. That makes sense. With these wake-activated neurons, if they have to just be constantly active and are starting to develop oxidative stress and proteins are misfiring, then it means that being awake for a really long time is probably a bad thing. But we just don’t know how long naps need to be. Is a nap of two hours sufficient to allowing the neurons to correct themselves and reset? We just don’t know that yet.

Dr. Sigrid Veasey, M.D., is a professor at Perelman School of Medicine at the University of Pennsylvania and the Center for Sleep and Circadian Neurobiology where she conducts research around sleep disorders and sleep disruption.