Sleep has a multitude of varying functions. Although universal in animals, many sleep systems that we as humans possess are unique and purposeful to our behaviour.
The functions of sleep include:
- DNA protection/repair
- Immune function
- Metabolism stabilization
- Hormonal regulation
- Pain sensitivity regulation (Moldofsky, 2001)
As we sleep, we cycle through different stages.
Light NREM: Non rapid eye movement with reduced muscular tone and slowing brain waves.
Deep NREM: Sleep spindle function important for memory consolidation, sensory gating (blocking stimulus) and further reduced muscular function.
REM: 20% of all sleep. Rapid eye movement with rapid brain waves and complete muscular paralysis.
The REM cycle consists of the dream state. Dreaming rapidly involves both cognitive (problem solving) and physical (coordinated movement) situational simulation and can be shown to increase performance if used purposefully (Samuels, 2008).
Not only is the REM cycle arguably the most important sleep state, but it is also the most easily disrupted with both behavioural and chemical influences.
The hypothalamus controls hormonal and ‘internal clock’ regulation, signaling to both the brain and body about how awake or how asleep we should be at any given time. This can be modulated by situation (first date = awake) or chemical (post Thanksgiving lunch = asleep)
Though universal, there is genetic contribution, with the general population in roughly three groups (chronotypes):
- 40% morning chronotype
- 30% evening chronotype
- 30% mixed
This chemical builds up in the brain during the day simply with general use. Interestingly, this is the mechanism affected by caffeine. The caffeine molecule is a competitive inhibitor to adenosine, meaning it attaches to the same receptor in the brain and blocks the sleepiness effect of adenosine. However, this is short lived as sleep is the only function that truly clears adenosine from the brain.
Optimize Your Sleep
Now that we understand the cyclical nature of both getting to sleep and sleep function, how can we optimize our sleep for the best daily performance?
- Avoid artificial light after the sun goes down (melatonin release)
- Regulate body temperature before sleep (cold is better) (Van Someren, 2006)
- Limit stimulants (caffeine, nicotine, cocaine) up to 4 hours before sleep
- Limit sedatives (alcohol, cannabis, opioids) – though they may help you get to sleep, they in fact inhibit the REM cycle and fracture the quality of your sleep (Garcia, 2015).
- Adhere to a consistent pre-sleep routine.
Written by: Zac Lewis, Osteopathic Manual Practitioner, Ace Sports Clinic
1. Moldofsky, Harvey. “Sleep and pain.” Science Direct, 2001, https://www.sciencedirect.com/science/article/abs/pii/S1087079201901790
2. Samuels, Charles. “Sleep, recovery and performance: The new frontier in high-performance athletics”. Science Direct, 2008. https://www.sciencedirect.com/science/article/abs/pii/S0733861907001351
3. Van Someren, Eus J.W. “ Mechanisms and functions of coupling between sleep and temperature rhythms”. Science Direct, 2006. https://www.sciencedirect.com/science/article/pii/S0079612306530183
4. Garcia, Alexandra. “Polysomnographic sleep disturbances in nicotine, caffeine, alcohol, cocaine, opioid, and cannabis use: A focused review”. Wiley, 2015.