Most Australians are sleeping less than they did previously. Some interesting facts from a study done by University of Adelaide in 2016:
- Average reported sleep time is 7 hours
- 28% of people report < 6hrs/night
- 12% sleep less than 5½ hours
- 76% report day time impairment or sleep-related symptoms
- People sleeping less than 7hr doubled since 1960
- 26% of Australians both use the internet most nights just before bed and have frequent sleep difficulties or daytime impairments
- Lack of sleep has a range of metabolic effects
Effects of Not Enough Sleep
The top 5 effects that happen when we do not get enough sleep are as follows:
- Stress sugar effect
- Brain needs energy to think. Searches for preferred energy source (glucose)
- Because it is deprived of sugar, reduced the control mechanism in the brain. We become more impulsive and search out food
- Brain reward system (seeks sugar foods), more active when low blood sugars. Pre frontal cortex that control this is deactivated
OUTCOME: We are more impulsive to look for sugary foods.
- Impaired glucose tolerance and effect when sleep 4-5 hrs/night
- Glucose clearance: 40% slower in the sleep-debt condition than in the sleep-recovery condition
- Glucose effectiveness: 30% lower in the sleep-debt condition than after the sleep-recovery condition
- Insulin response to glucose: 30% lower in the sleep-debt condition than in the deep-recovery condition
OUTCOME: We are less effective at managing the sugars and that leads to a greater risk of diabetes.
- A slowed resting metabolic rate. RMR is the energy required for our body to keep going. That is to keep warm, to think, to break down food.
- Sleep deprived for 3 weeks (5.6hr/night) with altered circadian rhythm – 28 hr days
- 8% reduction in RMR
OUTCOME: 8% reduction in RMR equates to a 6kg in weight gain over a 1 year period.
- Increased release of Ghrelin
- Ghrelin is the hunger hormone
- Release by GI tract – controls food intake in dose proportional manner
- Significantly increased in sleep deprived state
OUTCOME: WE are hungrier so we eat more food.
- Impaired leptin response
- Leptin is the satiety hormone. Release by adipocytes (fat cells)
- It increases metabolic rate, physical activity, decreases hunger
- 19% reduction in the amount released when sleep deprived
OUTCOME: WE are hungrier so we eat more food. We need more foods to feel full.