Impact of Sleep Deprivation
When sleep duration is altered by 1 hour, our cardiovascular health changes. There is a daylight savings time happens twice a year, one in spring and another in fall. In spring when we lose hour of sleep, there are increase in heart attack cases by 24%. In fall when we gain hour, there are 21% reduction in heart attack cases.
Lack of sleep promote sympathetic nervous system as the main driver, which is a fight or flight nervous system. This promotes increase in adrenaline release, elevated cortisol level, and decrease in growth hormone. In temporarily stimulation of sympathetic nervous system is important, especially when exercising. However, sympathetic nervous system as main driver is like full press on the gas pedal every time when driving the car, which will wear out the car quickly.
When sympathetic nervous system is the main driver, blood pressure will be increased, metabolism or mechanism to change the food to energy will be negatively affected. Because of high cortisol level, while dieting with under slept(<6hr) condition, 70% of weight loss may come from lean muscle mass. This may have negative impact towards muscle recovery after the workout.
When under slept, we are mentally less motivated to be physically active. Even when you motivate yourself to exercise, time to physical exhaustion drops by 30%. Which means, if you are planning to exercise for 60 min, you may experience physical exhaustion before 45th min. For soccer players, which total game duration is 90 minutes, physical exhaustion may kick in at around 60 minutes.
Sleep Deprivation and Diet/Exercise Outcome
Study has shown that people who limit their sleep to 4-6 hours for 1 week will have down regulated leptin, which is satiety hormone, and upregulated ghrelin, which is hunger hormone. They also found that people with 6 hours of sleep will consume extra calories during the following day.
There has been a study done in University of Chicago where group of healthy subjects got 4 hours of sleep for 2 weeks and see the glucose level primarily in muscles. There were 50% reduction in ability to put glucose into their muscles. Healthy blood sugar level is typically less than 100mg/dL and more than 200mg/dL would consider diabetic. After one week of sleep deprive, subjects had similar blood sugar level as pre-diabetics.
As mentioned before, when sleep deprived, 70% of weight loss is coming from muscle mass. On top of that, we may have more hunger and less satiated which make us unconsciously consume more food than we should. With all the food we eat, our glucose delivery to the muscle is reduced by 50% which also means that the muscle may not recovered from the physical activity that was performed to lose weight.
Sleep deprivation certainly is not the only reason why people cannot lose weight; however, it does seem to impact negatively on the outcome that people are looking to accomplish through diet and exercise.
Sleep Deprive and Growth Hormone
Reason why we workout is to get strong, look and feel great. However, men who gets 5-6 hours of sleep have testosterone level that is equivalent to men who are 10 years older and has smaller testicles and fewer sperm count. Sounds like side effect from performance enhancement drugs, right? Similar things may happen to women for their reproductive health and menstrual cycle.
Effect of Caffeine, Alcohol and High Carb Meal
Some people use alcohol before sleep thinking that it is a form of sleep aid. However, alcohol is sedative which is equivalent to someone hit you in a head with a bat to knock you out. Sedation is not a sleep. Alcohol also promotes fragment sleep, which means you may wake up multiple times during the night. Alcohol can also block our REM sleep, which makes you feel unrestored and unrefreshed in the morning. This is most likely due to alcohol raise your resting heartrate, body core temperature, which has negative effect to quality sleep. A meal high in sugar before bedtime, such as bowl of cereal, may have similar affect as alcohol.
Caffeine is commonly used to stay awake. From wakeful state in the morning to sleep state at night, our brain accumulates chemical called adenosine. Caffeine blocks adenosine receptor in brain, which acts like pause or mute button on sleepiness. Just like any other chemicals, caffeine also has half-life and quarter-life. For caffeine, half-life is 6 hours and quarter-life of 12 hours. What it means is that once the caffeine is in our body, it has affect for 12 hours. So, if you had a cup of coffee at 10am the affect of coffee may continue until 10pm. Even with those who say they can sleep after caffeine consumption, study has shown 20% reduction in deep sleep. This affect with caffeine may be differ from those who are sensitive to caffeine to those who are not.
4 Things to Improve Sleep
Avoid eating closely to the bedtime can promote acid reflux and digestive issue, which may interfere with sleep. You core temperature will increase after eating which can interfere with sleep. So, try finishing all caloric intake, both food and beverage, 3 hours prior to bedtime. This also led to another suggestion of keeping the bedroom cool to about 65-68 degrees Fahrenheit to drop your core temperature, which will promote sleep and stay asleep.
You can also optimize bedtime prep routine by turning off most of the light starting 90 min. before bedtime, which will help promote melatonin to prepare the sleep cycle. If you read on ipad or tablet there should be an option to reduce blue light. This will also help promote melatonin.
Although vigorous exercise raises core temperature and not suitable to do prior to bedtime, however, light stretching can relax the body and mind which can help with sleep.
Finally, be regular with sleep and wake schedule. We are creature of habits and better to create routine sleep schedule. If you are waking up at 6am you should be in bed by 10pm. Even if you cannot fall asleep initially, start your bedtime prep at same time every night.
Last Thought
We all are exercising for strength, looks, and health. When the muscle and strength growth is not happening, before looking into changing your workout, debating on should you have hormone replacement therapy, or trying new things you see on social media, it may be more beneficial to get 7-8 hours of sleep first.
Some bodybuilders suggest 3 hrs. of sleep is acceptable, however, number of studies have shown otherwise. “You can sleep when you are dead” is not a smart advise.
Even if you are sleeping 7-8 hours but not recovering properly, it may be a good investment to check for sleep apnea. Sleep is not a pillar for healthy lifestyle, but it is a foundation for exercise and nutrition to build on.
Kota Shimada
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