Sleep & Its Importance To Recovery

Sleep plays a pivotal role in recovery and therefore any disruption to sleep or reduction in the quality of sleep will delay recovery and therefore impede overall progress in training.

Sleep is extremely important for numerous biological functions and sleep deprivation can have significant effects on athletic performance, especially sub-maximal, prolonged exercise. From the available evidence it appears that athletes may be obtaining less than 8 h of sleep per night and that increasing sleep (sleep extension) or napping may be useful to increase the total number of hours of sleep and thereby enhance performance.

In normal sleep, the stages follow a structured sequence starting with wake, then light sleep with stages 1 and 2, followed by deep sleep (slow wave sleep) with stages 3 and 4, and then followed by REM sleep. Such a sequence is called a sleep cycle which has a typical duration of 90–110 min. A normal night consists of six sleep cycles where the proportion of deep sleep decreases from the beginning to the end of the night and the proportion of REM sleep increases at the same time. In summary, about 50–60% of time is spent in light sleep, 15–20% of time is spent in deep sleep, 20–25% is spent in REM sleep, and 5% or less is spent in wakefulness.

The autonomous nervous system changes with sleep. Heart rate, blood pressure, and respiratory rate are lowered to adapt to the reduced metabolic needs during normal sleep. Consequently, the mean heart-rate values drop from wakefulness to light sleep and further to deep sleep. During REM sleep heart rate increases again showing a high variability, which may exceed the variability observed during quiet wakefulness

The internal structure of sleep shows clear dynamics that follow a physiological imprinted pattern. This pattern can be described successfully by sleep stages ranging from light sleep to deep sleep and REM sleep. The dynamics of sleep stages can be investigated as such by analyzing the duration of sleep stages in the course of the night. The statistical analysis of sleep-stage durations revealed completely different patterns for the regulation of sleep stages and wakefulness episodes during sleep. This indicates that sleep and wakefulness are not just two parts of a sleep–wakefulness control, but that there exist entirely different mechanisms for their regulation in the brain. This fundamental mechanism is not altered in principle by sleep disorders that have a large impact on sleep fragmentation. Only the parameters of the distributions change.

The analysis of the autonomic nervous system during sleep by the investigation of heart-rate variability gives further insight into the regulation of sleep. We found that when the brain is very active as in the ‘dream’—REM stage, heart rate has long-time correlations, like in the wake phase. In contrast, in deep sleep correlations of the heart rate vanish after a small number of beats. In light sleep finally, the heart rate seems to become uncorrelated as well, but only after an increased number of beats. We also compared the altered autonomic nervous system function in obstructive sleep apnea with the results for normal subjects. We found that the differences between the sleep stages are much clearer than the differences between healthy and sleep apnea subjects. This means that the basic heart-rate control in the different sleep stages is very dominant. Obstructive sleep apnea introduces an additional variation on heart rate with a typical bradycardia/tachycardia pattern corresponding to the apnea events, but leaves the basic autonomous nervous system regulation untouched.

The autonomous nervous system changes with sleep. Heart rate, blood pressure, and respiratory rate are lowered to adapt to the reduced metabolic needs during normal sleep. Consequently, the mean heart-rate values drop from wakefulness to light sleep and further to deep sleep. During REM sleep heart rate increases again showing a high variability, which may exceed the variability observed during quiet wakefulness

1300146f3

The differences between healthy and sleep apnea subjects were much smaller than the differences between sleep stages. This indicates that the basic mechanisms for heart-rate control on an interbeat level did not change very much with sleep apnea. We assume that this basic mechanism is strongly controlled by sleep stages. It seems likely that the long-range correlations during wakefulness and REM sleep are caused by the enhanced influence of the brain on the autonomous nervous system. When this influence is strongly reduced, as is the case during light sleep and deep sleep, the heartbeat intervals behave in a more random fashion. Our studies support the view that there is a strong interaction between the central nervous sleep regulation and the autonomous nervous system regulation. Both systems interact and the measurable parameters cannot be interpreted without the knowledge about the current state of the other system.

The internal structure of sleep shows clear dynamics that follow a physiological imprinted pattern. This pattern can be described successfully by sleep stages ranging from light sleep to deep sleep and REM sleep. The dynamics of sleep stages can be investigated as such by analyzing the duration of sleep stages in the course of the night. The statistical analysis of sleep-stage durations revealed completely different patterns for the regulation of sleep stages and wakefulness episodes during sleep. This indicates that sleep and wakefulness are not just two parts of a sleep–wakefulness control, but that there exist entirely different mechanisms for their regulation in the brain. This fundamental mechanism is not altered in principle by sleep disorders that have a large impact on sleep fragmentation. Only the parameters of the distributions change.

The analysis of the autonomic nervous system during sleep by the investigation of heart-rate variability gives further insight into the regulation of sleep. We found that when the brain is very active as in the ‘dream’—REM stage, heart rate has long-time correlations, like in the wake phase. In contrast, in deep sleep correlations of the heart rate vanish after a small number of beats. In light sleep finally, the heart rate seems to become uncorrelated as well, but only after an increased number of beats. We also compared the altered autonomic nervous system function in obstructive sleep apnea with the results for normal subjects. We found that the differences between the sleep stages are much clearer than the differences between healthy and sleep apnea subjects. This means that the basic heart-rate control in the different sleep stages is very dominant. Obstructive sleep apnea introduces an additional variation on heart rate with a typical bradycardia/tachycardia pattern corresponding to the apnea events, but leaves the basic autonomous nervous system regulation untouched.

Our studies support the view that there is a strong interaction between the central nervous sleep regulation and the autonomous nervous system regulation. Both systems interact and the measurable parameters cannot be interpreted without the knowledge about the current state of the other system.

So, how can sleep be optimised to aid recovery?

  1. Humans sleep in five phases which repeat themselves every 90 minutes. Five cycles equates to seven-and-a-half hours which is enough for the average adult
  2. Take naps (up to 1 hour) – ideal time after lunch between 1-3
  3. The bedroom should be cool, dark and quiet
  4. Create a good sleep routine by going to bed at the same time and waking up at the same time
  5. Avoid watching television in bed, using the computer in bed and avoid watching the clock.
  6. Avoid caffeine approximately 4-5 h prior to sleep (this may vary among individuals)
  7. Do not go to bed after consuming too much fluid as it may result in waking up to use the bathroom
  8. Caffeine and liquids high in sugar are off the menu, as are fat-laden meals, which take longer to digest and raise body temperature, which in turn slows the process of falling to sleep
  9. Begin a pre-sleep routine 90 minutes before bed – start turning off televisions, mobile phones and other electrical devices which give off bright light.
  10. Have a shower prior to sleeping. Your body temperature will cool after coming out of the shower and ease you naturally into a state of sleep.
  11. Turn your radiator down – a cool 16-18C is ideal.
  12. Drink a glass of warm milk before bed. Dairy products are rich in tryptophan, which aids the production of sleep-inducing chemicals serotonin and melatonin.

As well as conditions like sleep apnea, alcohol, work stress and intensive exercise late in the day can limit our amount of deep sleep, whereas aerobic exercise and a regular pre-bed relaxation pattern can facilitate deep sleep. In fact, as summarized in this blog post , higher HRV before bedtime seems to enable a more rapid & effective transition to good quality sleep.

 

Advertisements

Mental Fatigue 13th October 2014

T a demanding 3-week training block in September I began to feel mentally as well as physically fatigued. originally, I had planned to take a one week recovery and then return to a new three-week training period, however, I have made a number of changes, notably:

  1. I have extended my recovery from one to two weeks
  2. I have decided to schedule two-week training periods followed by one week of recovery
  3. I will be joining a gym where they have a wider selection of weight resistance machines and run classes

During my recovery I have begun to realise that my mind as well as my body will eventually succumb to fatigue. Presumably there must be some kind of chemical imbalance that leads to mental fatigue – it is a defence mechanism to prevent one from overtraining and causing actual physical harm by way of an injury or illness. My HRV has come down from the low 70’s to about the high 50’s and has only recently started to climb again and I am reading this as a signal that my body is approaching recovery from a long accumulated period of training, from March right through until the end of September, that is, six months.

My position is to return to full training shortly and that means averaging around 100 TSS points per week for the two-week full-on training period and somewhere around 60-75 TSS points for the recovery week.

One positive over the past two-weeks has been my continued adherence to the performance-management diet. My weight is now 70.8kg and I feel confident that I can lower it to my target weight of 69.5kg within a few weeks.

Why Do I Cycle? 19/5/14

It is useful to reflect on why I put so much time, effort and money into cycling. It has become my number one pursuit and I have been actively cycling now for about two years.

There are occassions when I am out on a bike ride and I am finding it tough and I ask myself why I bother putting myself through all the pain. I think it is a good question, especially for those rides when it is particularly tough. It is on those occasions that I need to remind myself why I do it. So, why do I cycle?

  1. To lose weight (more precisely, to lose fat) – this was always my original goal. Losing weight and keeping it off has been my biggest challenge. I currently weigh 72.4kg and that has taken some time to get to. I am aiming to reduce my weight to 69.5kg – it is proving very difficult but slowly but surely the weight is coming off. If I didn’t cycle I would have no chance of losing any weight, not without losing muscle too. But why would I want to give up eating – why give up one of life’s pleasures. So, that is one of the top reasons for cycling; to lose weight and to keep it off whilst enjoying my food.
  2. To get fit and strong and have good tone and musculature – I am aware that every year, men over 40 lose 1% of their muscle mass. I have seen how older men lose their muscle and I don’t want this to happen to me. In order to maintain/build my muscle mass and build my strength I ride my bike and to aid my bike riding I train with weights in the gym.
  3. To feel exhilarated when I achieve a cycling goal or ride well. I won’t forget how good I felt after last years Ride London. I just could not believe that I had ridden 100 miles at an average speed of 18mph. It was just mind-blowing and I want to feel like that again. I can also feel exhilarated when I have ridden well on a long or hard ride. It is a fantastic feeling when you hit good form, however, it takes effort and hard work to achieve.
  4. One of the surprising benefits of bike riding is how many friends I have made. I suppose it is no surprise that I am able to bond with people with similar outlooks, people who want to keep fit and strong. Cycling attracts people from different backgrounds, young and old, and different demographics. The one thing that brings us together is our love of cycling. Training with other guys in pursuit of personal goals, lets say for a given sportive, is a great motivator for training, especially when the going gets tough. One shares the ups and downs of training.

Overall, it has to be said that cycling has given my life real focus. I have a pursuit that keeps me fit and strong, that allows me to carry on enjoying my food, and allows me to share the mixed emotions of cycling with like-minded people. I shall continue to set myself goals so I have something specific to aim for. I don’t think it is enough to just to ride for the sake of riding – there has to be a compelling goal to keep me going.