Sleep is an essential function – it allows the body and mind to recharge, and also helps combat diseases. Without enough sleep, the brain cannot function properly – impairing our ability to concentrate, think clearly and process memories.
But what causes us to have interrupted sleep?
Sleep Cycle
When we fall asleep, our bodies follow a sleep cycle. This cycle is broken up into 4 stages and repeats throughout the night:
Non-REM sleep:
- Stage 1: Transition between wakefulness and sleep (light sleep)
- Stage 2: Deeper sleep, eye movements cease, temperature drops
- Stage 3: Most important stage in making you feel alert and refreshed the next day. Heart rate, breathing and brainwave activity all reach lowest levels.
REM (Rapid Eye Movement) sleep:
- Eyes move back/forward quickly under eyelids
- Breathing rate, heart rate and blood pressure begin to increase
- Dreaming typically occurs during REM sleep, arms + legs become paralysed (thought to stop you physically acting out your dreams)
- Numerous studies have linked REM sleep to memory consolidation, the process of converting recently learned experiences into long-term memories.
What controls our sleep?
Chemical called ‘Adenosine’
- Adenosine levels rise continuously while you are awake, increasing the drive to sleep
- Level drops to baseline after approx 3 hours sleep
- Caffeine blocks adenosine receptors.
Internal ‘body clock’
- Sends messages to other parts of the brain, including the pineal gland which produces melatonin
- When light is detected by the eyes, the pineal gland stops producing melatonin.
A study comparing reading a hard copy book vs ebook before bed showed use of devices delayed the circadian clock, suppressed levels of melatonin, reduced the amount and delays in timing of REM sleep, and reduced alertness the next morning.
How much sleep should we be getting?
For most adults, at least 7 hours of sleep each night is needed for proper cognitive and behavioural functions.
What happens when we don’t get enough sleep?
- Sleep restriction leads to change in leptin and gherlin (hunger hormones) and therefore, increased calorie intake the next day. Individuals are unable to clear glucose or secrete insulin as efficiently.
- 90% of depressed patients have sleep complaints, and these precede the onset of depression in 40% of cases. If sleep disorders are not addressed, they are more likely to relapse.
- Those with <7 hours sleep time are 2.94 times more likely to develop a cold than those with > 8 hours.
- Normal subjects deprived of sleep reported a greater pain rating to noxious stimuli
- Not surprisingly, lack of sleep has been linked to a higher risk for certain diseases including obesity, type 2 diabetes, high blood pressure, heart disease, stroke, poor mental health and death.
How can you improve your nightly routine?
- Establish a realistic bedtime routine and stick to it every night, even on the weekends!
- Maintain comfortable temperature settings and low light levels in your bedroom
- Place a screen ban on TV, laptops, iPads, phones and other electronic devices in your bedroom.
- Exercise during the day, this can help you wind down in the evening and prepare for sleep.
- Avoid eating 3 hours before bedtime as it shunts blood flow to your core and increases your body’s temperature, and avoid caffeine after 12pm.
If you would like more information on sleep, visit the Sleep Foundation’s website
Disclaimer
All information is general and is not intended to be a substitute for professional medical advice.
