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Hibernation Hints at Dementia Therapy

Dementia Therapy

Story at-a-glance -

  • Hibernating mammals may lose up to 30 percent of their brain’s connections during hibernation, but the connections are restored come spring
  • Cold-shock proteins, which exist to help your body survive low temperatures, appear necessary to help restore the lost connections
  • Sleep and sleep loss modify the expression of several genes and gene products that may be important for synaptic plasticity and memory enhancement in humans

By Dr. Mercola

When animals hibernate, their body temperatures drop and their metabolism slows significantly (in some cases to just 2 percent of normal). In this state of virtual suspended animation, the animals’ brains show signs of changes akin to early-stage Alzheimer’s, and some even lose their memories.

Specifically, when animals hibernate the cooling induces a loss in synapses, which are the connections between brain cells. Synapses are also lost in the early stages of certain neurodegenerative diseases, including Alzheimer’s disease.

In humans the early loss of synapses typically progresses to the point that whole brain cells begin to die – and memories go along with them. Hibernating mammals may lose up to 30 percent of their brain’s connections during hibernation.

The connections are restored come spring, which has caught the attention of researchers wondering if restoring lost memories in humans might someday be possible.

Cold-Shock Proteins May Help Prevent Memory Loss

A new study published in Nature unraveled more clues about how hibernation might give clues to preventing dementia.1 When mice were artificially cooled, a number of cold-shock proteins, including RNA-binding protein (RBM3), were induced in the brain – a process that also occurs during hibernation.

Cold-shock proteins exist to help your body survive low temperatures (they’re at the other end of the spectrum from heat-shock proteins, which are induced by heat to help protect your body from heat stress).

All of the mice lost synapses during the study, but while older mice were not able to reestablish them when warmed up, young mice with neurodegenerative diseases regained their lost connections.

The difference was attributed to levels of RBM3, which “soared” in the young mice during cooling but not in the older mice. The researchers believe enhancing cold-shock pathways could offer potential protective therapies for neurodegenerative diseases, but they’re looking into ways of doing this other than cooling your body (which wouldn’t be practical for chronic treatment).

Interestingly, rapidly cooling the body has been suggested as a plausible medical treatment for a variety of conditions, from traumatic injuries to preventing brain damage from strokes.

Sleeping May Help You Enhance Your Memory

Research from Harvard indicates that people are 33 percent more likely to infer connections among distantly related ideas after sleeping,2 but few realize that their performance has actually improved.

Sleep is also known to enhance your memories and help you "practice" and improve your performance of challenging skills. In fact, a single night of sleeping only 4 to 6 hours can impact your ability to think clearly the next day.

The process of brain growth, or neuroplasticity, is believed to underlie your brain's capacity to control behavior, including learning and memory. Plasticity occurs when neurons are stimulated by events, or information, from the environment. However, sleep and sleep loss modify the expression of several genes and gene products that may be important for synaptic plasticity.

Furthermore, certain forms of long-term potentiation, a neural process associated with the laying down of learning and memory, can be elicited in sleep, suggesting synaptic connections are strengthened while you slumber.

To be clear, sleeping is not the same as hibernating. Hibernation would be more akin to resting in a coma than sleep, and research shows that animals often show signs of sleep deprivation upon waking from hibernation. As reported by Popular Science:3

When a mammal is in torpor [a short period of hibernation], it gets less rapid eye movement (REM) sleep and less slow wave sleep, because good sleep involves some physiological processes that require warmer body temperatures. Animals sleep a lot when they emerge from torpor, with brain activity patterns demonstrating signs of sleep deprivation.”

So while hibernation may hold clues to restoring memories related to lost synapses, hibernation does not appear to give the body the benefits of proper sleep, which are separate and equally important.

Naps Help Babies and Adults Retain Memories

There’s a reason why babies nap and, perhaps, why you should, too. Research shows that naps can give a boost to babies' brainpower. Specifically, infants who slept in between learning and testing sessions had a better ability to recognize patterns in new information, which signals an important change in memory that plays an essential role in cognitive development.4

New research also shows that napping for 30 minutes or more within 4 hours of learning a new behavior helps infants retain their memories.5 The results suggest that infants rely on frequent naps to help form long-term memories, and there's reason to believe this holds true for adults, too.

Even among adults, a mid-day nap was found to dramatically boost and restore brainpower.6 Dr. Rubin Naiman -- a clinical psychologist, author, teacher, and the leader in integrative medicine approaches to sleep and dreams – believes that humans are biologically programmed to nap, so if you feel the urge to nod off in the afternoon, don’t fight it.

The “ideal” nap time appears to be around 20 minutes (any longer and you’ll enter the deeper stages of sleep and may feel groggy when you wake up). According to the National Sleep Foundation:7

“Sleeping for a short time can make you more alert and energetic--this might be critical to your work or school productivity, or to your ability to take care of a child during the day. Most people feel refreshed after a nap that lasts approximately 20 minutes.”

At Nighttime You Should Strive for Uninterrupted Sleep

While many animals engage in torpor, which is basically shorter periods of interrupted hibernation, humans need uninterrupted sleep to function properly. It makes sense that interruptions to your sleep would result in much the same damage as lack of sleep, because sleep occurs in phases.

Ideally, you should progress from slow-wave sleep back up to REM sleep in 60- to 90-minute cycles. Any interruptions to this make your body start over in a sense, which means you might never reach the most restorative, deeper phases of sleep. 

You might as well not be sleeping at all, which is likely one reason why lack of sleep and interrupted sleep result in such similar damage. In a healthy night’s sleep, you should progress through the following sleep stages (though not necessarily in this order):8

  • Stage One, when you’re preparing to drift off
  • Stage Two, during which your brain wave activity becomes rapid and rhythmic while your body temperature drops and heart rate slows
  • Stage Three, when deep slow brain waves emerge (this is a transition from light sleep to deep sleep)
  • Stage Four, also known as delta sleep, this is a deep sleep stage
  • Stage Five, or rapid eye movement (REM) sleep, is when most dreaming occurs

As reported by Psych Central:9

“Sleep does not progress through all of these stages in sequence, however. Sleep begins in Stage One and progresses into stages 2, 3, and 4. Then, after Stage Four sleep, Stages Three, then Two are repeated before going into REM sleep.

Once REM is over, we usually return to Stage Two sleep. Sleep cycles through these stages approximately 4 or 5 times throughout the night. We typically enter REM approximately 90 minutes after falling asleep. The first cycle of REM often lasts only a short amount of time, but each cycle becomes longer.

This is why we need long periods of sleep each night as most of the REM sleep occurs in the hours before awakening. If we get short periods of sleep, we can’t really get through the stages we need to heal and stay healthy. REM can last up to an hour as our sleep progresses. In case you are wondering, if you feel like a dream is taking a long period of time, it really is. Contrary to what was once believed, dreams take as long as they actually seem.”

Keep Your Phone and Tablet Out of Your Bedroom

One of the greatest plights of modern-day sleep is the introduction of light-emitting electronic devices to the bedroom. Research shows that 90 percent of Americans use an electronic device within an hour of going to bed, and this is associated with poor sleep.10 A new study also compared the use of an iPad for 4 hours before bed (for five consecutive nights) to reading a print book for the same period.11 There were significant biological effects of iPad use before bed, including:12

  • Reduced secretion of melatonin, a hormone that induces sleepiness
  • Delayed circadian rhythm of more than an hour
  • Feeling less sleepy before bedtime
  • Feeling sleepier and less alert the following morning, even after 8 hours of sleep
  • Spending less time in REM sleep

One of the study’s authors noted: "We found the body's natural circadian rhythms were interrupted by the short-wavelength enriched light, otherwise known as blue light, from these electronic devices.” The blue light emitted from electronics such as cell phones, tablets, TVs and computers suppresses your melatonin production, thereby preventing you from feeling sleepy. What you may not realize is that even if you don't feel sleepy, you need sleep. You've simply artificially disrupted your body clock; you have not in any way altered your body's biological needs. Last year I interviewed Dan Pardi on the topic of how to get restorative, health-promoting sleep. 

Pardi is a researcher who works with the Behavioral Sciences Department at Stanford University and the Departments of Neurology and Endocrinology at Leiden University in the Netherlands.In addition to avoiding blue light at night, Pardi recommends getting at least 30-60 minutes of outdoor light exposure during daylight hours in order to "anchor" your master clock rhythm. The ideal time to go outdoors is right around solar noon but any time during daylight hours is useful. Once the sun has set, the converse applies. After sunset you want to avoid light as much as possible in order for your body to secrete melatonin, which helps you feel sleepy.

Download Interview Transcript

You Probably Need to Go to Bed Earlier Than You Think

You may be surprised at how little sleep you’re actually getting. If you go to bed at 10 pm and get out of bed at 7 am, you might say you’ve slept for nine hours. In reality, you probably spent at least 15-30 minutes falling asleep and may have woken during the night one or more times. With the advent of fitness-tracking wristbands such as Jawbone’s UP, however, it’s now possible to track your actual sleep time. When I first started using a fitness tracker, I was striving to get 8 hours of sleep, but my Jawbone UP typically recorded me at 7.5 to 7.75.

I have been using an UP tracker for the last six months and just the last month have finally been able to restructure my schedule so that I am getting close to 9 hours of sleep. Quite a contrast from when I was seeing patients, as it would typically be far closer to an unhealthy 5 hours or less. I have since increased my sleep time, not just time in bed, but total sleep time to over 8 hours per day. The fitness tracker helped me realize that unless I am asleep, not just in bed, but asleep by 10 pm I won’t get my 8 hours. Gradually I have been able to get this down to 9:30 pm.

The tracker also differentiates between sound and light sleep, and through trial and error, I was able to use the device to figure out I can get 6 hours of deep sleep if I maintain my air temperature around 66-68 degrees F with only a light sheet on. If it is much warmer or I use a blanket, my sound sleep can drop to 2-3. Pardi recently shared how having a baby has helped to improve his overall sleep because it got him in the habit of going to sleep earlier, and importantly, getting into bed prior to feeling sleepy. He explains:13

Yes, having a baby has improved my overall sleep practice. Because of my son, we wind our evening down earlier than normal in order to get him to bed at a good time for him. Since we must initiate these activities earlier than what we would do for ourselves, it has gotten us into the habit of thinking of sleep earlier than normal.

Specifically, I get into bed earlier than I used to. Now, I will read my kindle, with dim backlight, in a room with amber-toned environmental light, and as soon as the urge for sleep strikes, all I have to do is put down the book. Most people, on the other hand, initiate their going-to-bed ‘program’ once they start to feel sleepy.

So, instead of being able to actually allow sleep to happen at this instance, you need to do a list of things – like brush your teeth, move yourself into bed, etc. – before you’re able to close your eyes. Because you’re sleepy, you’re likely to move slowly to accomplish this list, and it’s easy to see how maintaining this latter pattern cuts into total sleep time; even 30 minutes of less sleep per night on a regular basis matters!  You don’t have to have a young child to benefit from this lesson: get into bed prior to when you want to be sleeping so you can give into the impulse as soon as it hits.”

Longing for a Good Night’s Sleep? Try These Tips

To achieve more restful, restorative sleep, I suggest you read through my full set of 33 healthy sleep guidelines for all of the details, but to start, consider implementing the following changes:

  • Avoid watching TV or using your computer in the evening, at least an hour or so before going to bed. These devices emit blue light, which tricks your brain into thinking it's still daytime. Normally, your brain starts secreting melatonin between 9 pm and 10 pm, and these devices emit light that may stifle that process.
  • Even the American Medical Association now states:14  “…nighttime electric light can disrupt circadian rhythms in humans and documents the rapidly advancing understanding from basic science of how disruption of circadian rhythmicity affects aspects of physiology with direct links to human health, such as cell cycle regulation, DNA damage response, and metabolism.”

  • Make sure you get BRIGHT sun exposure regularly. Your pineal gland produces melatonin roughly in approximation to the contrast of bright sun exposure in the day and complete darkness at night. If you are in darkness all day long, it can't appreciate the difference and will not optimize your melatonin production.
  • Sleep in complete darkness, or as close to it as possible. The slightest bit of light in your bedroom can disrupt your body’s clock and your pineal gland's melatonin production. Even the tiniest glow from your clock radio could be interfering with your sleep, so cover your radio up at night or get rid of it altogether. Move all electrical devices at least three feet away from your bed. You may want to cover your windows with drapes or blackout shades. If this isn’t possible, wear an eye mask.
  • Install a low-wattage yellow, orange, or red light bulb if you need a source of light for navigation at night. Light in these bandwidths does not shut down melatonin production in the way that white and blue bandwidth light does. Salt lamps are handy for this purpose. You can also download a free application called F.lux that automatically dims your monitor or screens.15
  • Keep the temperature in your bedroom no higher than 70 degrees F. Many people keep their homes too warm (particularly their upstairs bedrooms). Studies show that the optimal room temperature for sleep is between 60 to 68 degrees F.
  • Take a hot bath 90 to 120 minutes before bedtime. This increases your core body temperature, and when you get out of the bath it abruptly drops, signaling your body that you are ready to sleep.
  • Avoid using loud alarm clocks. Being jolted awake each morning can be very stressful. If you are regularly getting enough sleep, you might not even need an alarm.
  • Get some sun in the morning, if possible. Your circadian system needs bright light to reset itself. Ten to 15 minutes of morning sunlight will send a strong message to your internal clock that day has arrived, making it less likely to be confused by weaker light signals during the night. More sunlight exposure is required as you age.
  • Be mindful of electromagnetic fields (EMFs) in your bedroom. EMFs can disrupt your pineal gland and its melatonin production, and may have other negative biological effects as well. A gauss meter is required if you want to measure EMF levels in various areas of your home. Ideally, you should turn off any wireless router while you are sleeping. You don’t need the Internet on when you are asleep.