The desperate quest to fall asleep, stay asleep and feel rested as we move through our daily lives is a common goal for many people. The effects of sleep deprivation become obvious if you miss just a couple of hours over a few nights. In light of the high incidence of sleep disorders, more and more researchers are looking at what makes us sleep, the effects of not sleeping and what we can do about it. As yoga teachers and practitioners, there can be a tendency to prescribe yoga as a cure-all for everything. While this habit stems from authentic experiences of yoga’s transformative effects, it’s important to understand how and why yoga might work. This publication will look at how sleep works and how yoga might help from an evidence-based perspective.

The following interview was conducted with Dr. Kamyar Soghrati MD FCCP FRCPC, a Respirologist and Sleep Medicine Specialist in order to answer some of the above questions.

Q: What is the function of sleep?

A: Dr. Soghrati:

There are ecological theories of sleep – for example, mammals hide during certain periods so that they are protected while recovering and likewise other mammals go into hibernation during cold periods when food will be scarce.

More importantly though, sleep in humans is associated with learning. It’s not just an inactive process like turning off a computer, the brain is active in that it is sorting through events of the day, processing information and storing it in a cohesive fashion. Moreover, neurotransmitter generation occurs during deep or slow wave sleep and virtually all neurotransmitters are associated with sleep generation and maintenance (i.e.: serotonin, nor-epinephrine, histamine, adenosine, acetylcholine etc.).

Q: Can you describe the stages of sleep and what’s happening to our brain during these stages?

A: Dr. Soghrati:

There are four stages of sleep in total. Stages N1, N2 and N3 get progressively deeper, ending in the fourth stage known as Rapid Eye Movement (REM). REM is closest to our waking state and is the stage that we do most of our dreaming in. In infants REM is called “active sleep”.

One of the reasons that infants are difficult to wake when they initially fall asleep is that they have a tendency to go into N3 right away, which is a very stable, deep and restorative sleep. Conversely, adults spend a greater proportion of time in N1 and N2 and it’s much easier to wake from these stages.

If you observe someone in REM, especially a child, you’ll notice muscle twitches, eye movements and an erratic heart and respiratory rate. Interestingly, when adults are in REM, all the muscles in the body-except the diaphragm-are paralyzed by the brain. This evolutionary development allows us to continue breathing and yet prevents us from acting out our dreams.

In general each cycle of sleep for an adult from superficial sleep to REM occurs over 90-120 minutes with 5-6 cycles occurring per night. For the first half of the night you have more slow wave sleep, which is mostly stage 3 and for the latter half of the night there is more REM sleep.

If we look at the brain itself when the eyes are closed and we’re resting, we’re generating alpha rhythms, which have a fairly high frequency. As we move through the stages of sleep the brain waves decrease and their amplitude increases, so it’s as if everything begins to fire together. Imagine being in a noisy room, where there are sounds coming from every direction without resonance or harmony – this is an awake state. Then imagine being in the same room and experiencing synchronicity and resonance – so that the incongruent sounds fade away and everything moves together – this is deep sleep.

Q: Why do some people wake up remembering their dreams, while others don’t?

A: Dr. Soghrati:

Dreams mostly occur in REM sleep, but can also occur in N3 or deep slow wave sleep (N3). In order to remember the dream, you need to wake up in that stage of sleep. So when people think they don’t dream, it’s not that they don’t, but that they’re not waking up in the midst of their cycle.

The difference between dreaming in N3 and REM is well illustrated when looking at the difference between a nightmare and a night terror in a child. When a child wakes from a nightmare, they wake up afraid, yet are able to recount the dream, understand that what they experienced was a dream and are able to be soothed. This is an example of waking up during REM sleep. When a child experiences a night terror, they might exhibit signs of having a scary dream, yet are very difficult to wake. Once woken, they will be extremely frightened and difficult to console, with an increased heart and respiratory rate. This is an example of waking up during N3 sleep.

So both nightmares and night terrors are dreams – they just happen in different stages of sleep.

Q: What happens to our sleep patterns as we age? How much sleep do we need at night?

A: Dr. Soghrati:

In general, as you age, you lose the ability to sleep, so in some ways we all become insomniacs as we grow older. An elderly person might naturally wake at 4 or 5 am, while a teenager can maintain sleep sometimes until noon. It’s almost like a degeneration of neurons that are necessary to maintain sleep, thus decreasing sleep efficiency.

Older people will experience much less N3 sleep, and spend more time in N1 and N2 sleep – REM remains the same. Because restorative sleep changes as we get older, one could argue that perhaps that stage is required for knowledge processing, storage and consolidation, and as we get older this becomes less important – this is just a theory though.

The number of hours of sleep is also age dependant. An infant can sleep up to 18 hours per day, versus a teen for 12 hours and adult for 7-8 hours. It’s always a bell curve so if normal for an adult is 7-8 hours, you will find some people that need 6 hours, while others do best with 9 hours. Interestingly, teenagers need more sleep and will also tend to go to bed later and night as well as get up later in the morning.

Q: Can you catch up on missed sleep?

A: Dr. Soghrati:

You can definitely catch up on sleep. If it’s acute sleep deprivation, you can recover your sleep over 2-3 days of sleeping appropriate hours. If it’s chronic sleep deprivation, it takes 2-4 weeks to recover through sleeping appropriate hours.

Q: Can you explain sleep onset from a scientific perspective? What makes us tired?

A: Dr. Soghrati:

The neurotransmitter adenosine is a sleep promoter. The longer you’re awake, the more adenosine you accumulate, and the more you have, the sleepier you’ll be. As you sleep, adenosine levels drop which makes you move towards a waking or alert state. Certain substances (i.e.: caffeine) will actually reverse or block adenosine receptors, inhibiting sleep for a period of time.

There is also the concept of “regional sleep”. Adenosine will build up in areas of the brain that are in high use, which means that some parts of the brain will become sleepier than others. For example, if someone is driving and drowsy, some parts of the brain are actually falling asleep, while others are awake (even though the eyes are open and they appear to be awake) and in this case the drivers performance is significantly sub-optimal.

Q: What are the effects of sleep deprivation? How does sleep deprivation affect our health?

A: Dr. Soghrati:

Loss of sleep will cause you to make errors of omission and commission. An example of an error of omission is that I might ask you a question and you would actually fail to compute that I’m asking you something. An error of commission occurs when you’re asked something while being drowsy, and you realize that you need to respond, however your processing is impaired (i.e.: you might say 2+2=3).

The emerging field of sleep deprivation and health consequences is providing strong evidence that restful sleep is essential. Long-term observational studies have shown a direct link between sleep deprivation and mortality. Further, sleep deprivation is associated with cardiovascular risk (i.e.: hypertension and heart attack), an increase in motor vehicle accidents and impairment of neurocognitive function (i.e.: perception, memory, behaviour). Mood disorders, particularly depression, have close links to sleep deprivation as well.

For example, if you take healthy university students with no mood disturbance and sleep deprive them over a period of 4-6 weeks; they will begin to exhibit symptoms of depression. Depression in turn causes sleep disturbance, so it becomes a vicious cycle.

Aside from these health impacts, there are some studies that indicate an association between sleep deprivation in female shift workers and infertility as well as cancer. While these results have been reported, they are both controversial and not well established. Perhaps the infertility is associated with a shift in circadian rhythms, which are intimately linked to the endocrine system.

Q: What are circadian rhythms?

A: Dr. Soghrati:

Circadian rhythms are a very primal part of all organisms – even cockroaches have them. The rhythm is an internal clock that influences your cycles of sleep, links to many organs and most importantly, impacts endocrine secretions. The human circadian rhythm is approximately 24.2 – 24.4 hours long. In general, our internal clock aligns itself with the 24 hour environmental light/dark cycle as well as social cues (alarm clock).

There has been a lot of research exploring where this clock hides. Scientists have asked, is it in the brain? The endocrine system? How does it keep that time?

What’s fascinating is that they found that it’s actually a molecular clock – meaning that it’s a clock that exists in every single cell. It is associated with a cycle that occurs in your DNA transcription in each individual cell every 24.2 to 24.4 hours.

Q: What are the common reasons for seeing the support of a Sleep Medicine Specialist?

A: Dr. Soghrati:

The two most common reasons for seeking support from a sleep medicine specialist are insomnia and sleep disordered breathing (sleep apnea). Insomnia affects 10% of the general population and every person has an 80-90% chance of developing insomnia at some point in life (in relation to stressors). In those suffering from mood disorders such as anxiety or depression, there is and 80-90% chance of insomnia. The third most common presentation is restless leg syndrome. In the pediatric population the most common reason for seeking help is parasomnias (i.e.: sleep talking, sleep walking, night terrors).

Q: What are the recommended treatments for insomnia? Does yoga help?

A: Dr. Soghrati:

Insomnia is often related to habitual, learned, maladaptive behaviours that perpetuate the inability to sleep.

The development of good sleep hygiene is the first recommendation. It includes:

Develop a regular sleep onset/offset (bedtime/wake time) even on weekends
Develop a winding down routine 1-2 hours prior to sleep – no computer or television-focus on relaxation
No vigorous cardiovascular exercise after 6-7 pm
Avoidance of stimulants (caffeine, nicotine and alcohol), any caffeine after 12 noon can disturb your sleep
Cultivate a cool, quiet, dark sleep environment where you feel safe
Avoid napping during the day – this is the worst thing you can do for your nighttime sleep
Cognitive behavioural therapy also works extremely well for those with insomnia. The three things that are most effective are; sleep restriction therapy, stimulus reduction and relaxation therapy.

Sleep restriction involves going to sleep only when you feel sleepy and not sooner. With stimulus reduction you only stay in bed for 20 minutes and if you’re not asleep, you get up, leave the bedroom and sit on the sofa reading quietly until you’re sleepy.

If there are intrusive thoughts about your day, or things you need to do in the future, get up and leave the bedroom. Write your ideas down on a piece of paper and symbolically leave that paper outside the bedroom door so that you’re brain knows that you will deal with it, but not now.

If you lie in bed tossing in turning for more than 20 minutes, the brain will become frustrated. It’s important to realize that YOU CAN’T FORCE SLEEP. Getting to sleep is not an active process, it’s passive, you need to allow it to happen. Because you can’t force sleep, you need to break the internal mental chatter that says, “I must sleep….tomorrow is a big day….etc.…”

Relaxation therapy includes deep breathing exercises, progressive muscle relaxation and restorative/yin styles of yoga. These techniques all optimally facilitate the parasympathetic nervous system (the rest/digest response). If you compare an insomniac to someone with regular sleep patterns, you’ll find that an insomniac has increased heart rate, respiratory rate and muscle tone during sleep AND waking states. Thus it becomes important to reduce this overall hyper-arousal. Research has also shown that cardiovascular exercise before 6-7 pm can help as well. Finally, guided imagery is also used, but is less effective than progressive muscle relaxation.

Visit http://traceysoghrati.com/download_audio for guided relaxation practices.

Dr. Kamyar Soghrati MD, FCCP FRCPC, Respiratory & Sleep Medicine, works at Credit Valley Hospital and the Toronto Sleep Institute.