Why do we sleep?

According to Harvard University studies, we aren’t quite sure. Here are four theories that have been discussed over the years:

1.  Inactivity Theory:

One of the earliest theories of sleep, sometimes called the adaptive or evolutionary theory, suggests that inactivity at night is an adaptation that served a survival function by keeping organisms out of harm’s way at times when they would be particularly vulnerable. The theory suggests that animals that were able to stay still and quiet during these periods of vulnerability had an advantage over the other animals that remained active. These animals did not have accidents during activities in the dark and were not killed by predators. Through natural selection, this behavioral strategy presumably evolved to become what we now recognize as sleep.

2.  Energy Conservation Theory

In humans, the energy metabolism is significantly reduced by as much as 10 percent when we sleep, even more in other species. Both body temperature and caloric demand decrease during sleep, as compared to wakefulness. The Energy Conservation Theory suggests that the primary function of sleep is to reduce an individual’s energy demand and expenditure during part of the day or night, especially at times when it is least efficient to search for food. Because we live in a society where food is plentiful, we don’t often think about the fact that one of the strongest factors in natural selection is competition for and effective utilization of energy resources.

3.  Restorative Theory

This theory is based on the long-held belief that sleep in some way serves to “restore” what is lost in the body while we are awake. Sleep provides an opportunity for the body to repair and rejuvenate itself. These ideas have gained support in recent years from evidence collected in human and animal studies. Animals deprived entirely of sleep lose all immune function and die within just a matter of weeks. This is also supported by findings that many of the major restorative functions in the body like muscle growth, tissue repair, protein synthesis, and growth hormone release occur, mostly or in some cases only during sleep.

4.  Brain Plasticity Theory

One of the most recent and compelling explanations for why we sleep is based on findings that sleep is correlated to changes in the structure of organization of the brain. This phenomenon, known as brain plasticity, is not entirely understood, but its connection to sleep has several critical implications.

Sleep plays a critical role in brain development in infants and young children. Infants spend about 13 to 14 hours per day sleeping, and about half of that time is spent in REM sleep, the stage in which most dreams occur. A link between sleep and brain plasticity is becoming clear in adults as well. This is seen in the effect that sleep and sleep deprivation have on people’s ability to learn and perform a variety of tasks. (Harvard School of Medicine) http://healthysleep.med.harvard.edu/healthy/matters/benefits-of-sleep/why-do-we-sleep

Another study suggests that not getting enough sleep directly impacts how healthy we are. Diseases like cardiovascular (hypertension and stroke), diabetes and obesity and weight gain tend to occur more often to those that are sleep deprived. Not sleeping enough promotes poor regulation of some of the hormones that control appetite and hunger cause you to eat more and thus gain weight. And finally, people who don’t get enough sleep don’t live as long as people who do.

A study that was done–and I have thought about this for years–looked at doctors’ work shifts. New interns work 2 shifts a week over 30 hours each. And they are expected to do that for 3-7 years of residency. This scheduling is almost like a rite of passage in the profession, but it seems crazy to me.  I certainly don’t want a sleep deprived doctor in charge of my health! I know this means that as a patient you may only have to work with one doctor and not have to change in the middle of your care, but physicians should not be working if they are no longer alert and thinking clearly. In fact, what was revealed in the study was that one out of five doctors reported fatigue-related mistakes that had injured a patient. One out of twenty reported fatigue-related mistakes that resulted in the death of a patient. Not only were these doctors a danger to their patients, but they were also a danger to themselves. Driving home after one of these marathon shifts, the likelihood that they would cause an accident increases by 165%.  One out of every five accidents is because the driver was sleep-deprived. In fact, every hour a person dies in a sleep related accident. This study leads us to believe that we must have enough sleep to think and understand clearly as well as be safe.

How much sleep do we need?

Even though we may not understand why we sleep, we all agree that it is important. It is often said that we can only know the “truth” if we have experienced it. Most of us can admit that we feel better when we have gotten a good night’s sleep.

The National Heart, Lung and Blood Institute confirms that there is no magic number as to the hours one needs to sleep at night, as individual sleep needs vary. Some suggestions they give however are:

This may sound like a lot; in fact I remember reading somewhere that President Bill Clinton only sleeps 4 hours a night.

Falling Asleep

To fall asleep, the body must be able to dissipate heat. If the room is too warm, the body won’t be able to do that. We know from studies that 60-67 degrees is the optimal temperature for sleeping and temperatures above 75 degrees and below 54 degrees are disruptive to sleep. We also know that cool temperatures are conducive for deeper sleep, and deeper sleep is more beneficial in healing.

Let’s take this idea one step further. Ayurveda uses a clock to explain many of its theories. For instance, the hours of 10am to 2pm and 10pm to 2am, constitutes pitta time, or a time that the body is hotter (metabolism is up). Pitta consists of the elements of fire and water. The qualities (gunas) of pitta are oily, sharp, penetrating, hot, and light. This is the time of day in which you are terribly busy getting things done, including eating lunch, the biggest meal of the day which is made easier to digest with an increased metabolism. The evening and early morning (10pm-2am), it is the time in which the body is cleansing and healing. This explains why after 10pm we seem to get a “second wind” and therefore cannot go to sleep until after 2am, when the vata time sets in, which has a cooling effect on the body.

Other theories suggest that sometimes when we cannot go to sleep it is because we are too exhausted to sleep. We just don’t have the energy to push us into the sleep cycle. This theory of energy could also explain why we are unable to stay asleep (Ayurvedic theory above) when the body heats up to cleanse and rejuvenate.

Some ideas that might help if you cannot go to sleep at night:

1. Go to bed by 9:30pm so that you are asleep by 10pm.
2. Make sure your room is cool (60-67 degrees), and dark.

This goes back to the Ayurvedic idea outlined above that after 10pm you enter pitta time and the core body will heat up. Consider how long it takes you to get ready for bed, and how long you lie in bed before falling asleep and take that time into consideration when determining your bed “time”. It may be 9pm instead of 9:30pm. The temperature of your bedroom is important; try different degrees and see which works best for you. Cover lights, even those of your clock, as they can be distracting.

3. Make dinner your smallest meal of the day.
4. Eat easy-to-metabolize food for dinner.
5. Finish dinner at least 3 hours before going to bed.

The body, regardless of time of day, will heat up to metabolize food. The less food you eat, the less time it takes to metabolize. Also, the type of food you eat is important. It takes less time and heat (energy) to metabolize cooked, warm food, than it does cold, raw food. Ayurveda looks at cooked food as pre-digested food. I know that doesn’t sound very appealing, but when you think that part of the digestive process is the breaking down of food into individual nutrients by heating it up, it makes sense. Plan on giving this process at least 3 hours. By that time, the body has cooled down and will have an easier time going to sleep. If you need a “digestive system” refresher course, read the past blogs:

• Understanding Digestion (Part One)
• Digestion (Part Two)
• Digestion (Part Three)
• Ayurveda’s View of Digestion
• Ayurveda’s View of Digestion (Part Two)

Note: Remember Dr. John Douillard’s theory about how the “janitor” comes at 10pm. If the food is not out of the digestion system when the body is ready to cleanse, it cannot perform the task which leads to rejuvenation. If this happens occasionally, not such a big deal, but if you eat late every night, eventually the “Janitor” gets the point and no longer shows up and the body eventually deteriorates causing illness and aging.

6. Avoid eating or drinking caffeinated foods. Not much explanation needed here. Caffeine is a stimulant.

7. Take a warm bath.
8. Drink warm milk or tea (see article on turmeric milk).

I know this seems counter intuitive. If you take a warm bath, your body will warm up. However, when you step out of the bath, the cold air helps spur the body to reduce its temperature.

Note:

• If you take a warm bath, make it yummy by add some sleep-inducing aromatherapy oil. The oil will cling to your skin as you get out of the tub and continue to lull you to sleep.
• If you drink warm milk, the body will want to dissipate the heat out through the skin and the core temperature of the body will eventually drop.

9. Meditate and/or gentle yoga.
10. Journal (brain dump).

The sympathetic nervous system is referred to as your “fight or flight” system. If you are all wound up before going to bed, it will take longer for you to fall asleep. So be careful to not watch a stimulating movie, take a spin class or read an adventurous book before going to bed. The para-sympathetic nervous system is known as the “rest and digest” system. Try gentler approaches (less stimulating) like meditation, yoga, journalism.

11. Wear comfortable clothing or go commando.
12. Make sure you have a comfortable mattress, pillow, and clean sheets.
13. Blankets should be light not heavy.

Consider your sense of touch not only in the temperature of the room but also what is right next to your body. Even the slightest stimulant will keep you awake (well not all of them, but we won’t get into the sex part of this). If you wear clothes to bed, keep them light, without buttons or zippers and in fabrics that breathe. Blankets that are too heavy makes it difficult to move around on your bed and work requires energy and produces heat. Light blankets can keep you warm enough and be less restrictive. Light down comforters are great!

A supportive mattress will let your body relax. Casper is a new sleep start-up company out of New York specializing in memory foam mattresses. Check them out at their website: www.casper.com.

Note: I get asked all the time by my yoga students why they can go to sleep on their mat at the end of yoga class but can’t go to sleep in their beds at night. And, of course, we have already discussed many of those reasons already in this article, but there is something to be said about knowing that you will be supported, whether it is by the earth underneath you like in yoga class (mat on a wood floor), or a supportive mattress. It lends to your ability to surrender.

Staying Asleep

Going to sleep may not be a problem but staying asleep may be. What causes us to wake up after we have begun sleeping? Let’s go back to the Ayurvedic clock theory. After pitta time (10pm to 2am) comes vata time (2am–6am and 2pm-6pm). The qualities (gunas) of vata are light, cool, mobile, dry, rough, and subtle. The vata elements are air and space. When the vata starts moving in the body if you don’t have enough energy to stay asleep, you will wake up. And of course, if you don’t have enough energy to stay asleep, chances are you don’t have enough to go back to sleep. In all reality, vata begins to move to help you eventually wake up. But if vata is too high, this will happen before you are fully rested.

Other reasons that you may wake up in the middle of the night could be that you are experiencing hormone release (night sweats), you may have taken in too much water too close to bedtime, or you are anxious (stressed) and your senses are on high alert–your teenager has a curfew and you may or may not have heard them come in the door yet. Here are some ideas that may help:

1. Do not drink alcohol.

Not only is alcohol poisonous to your system, it is also heating (fire water!) But alcohol, as it metabolizes, reacts more like a stimulant and wakes you up even though you may think has a calming effect.

2. Keep pets out of the room
3. Address your partner’s snoring
4. Consider the ideas listed in the “Why you can’t go to sleep” category.

So, I think we can conclude that our lifestyle choices, food choices, and environment play a large role in our ability to get a good night’s sleep.  We must make a conscious effort to make sleep a priority.  On that note, I must say “goodnight” and go to bed.  It is midnight (and I probably will not get to sleep until 2am) and I have a busy day tomorrow with Ayurveda clients and Yoga students. A teaspoon of my own medicine please.

Thank you always for reading my blog and sharing it with your friends.

I also wanted to thank my sister, Jackie Kogan, for editing this article.  I really appreciate you and your ability to make my blogs better.