Helping with sleep – Introduction.
Almost 1 in 3 people globally will suffer from some sort of sleep disturbance in the next year. Poor sleep can affect the way we eat, our mood and relationships, our jobs and productivity and how active and fit we are, so the effect on our health is huge.
Sadly, not much is known about sleep disturbances, or indeed sleep itself. Much of that is down to a lack of research on sleep and that is down to sleep being unmarketable. We simply can’t package and sell it like exercise and nutrition so there’s limited funding to the research.
However, sleep disturbances or insomnia cannot be ignored and it’s worth knowing what happens when we sleep and what to do when it goes wrong. In the first in a three-part feature, Mold Physiotherapy will lift the lid on sleep and how we can help you get a better nights’ rest.
Part one will look at the what we know about sleep so far. Part two looks at what can go wrong, and part three will look at some practical steps that can be taken to sleep better for life.
Sleep, what we know.
Sleep falls into two segments NREM and REM sleep.
The first segment of sleep is NREM, or ‘non-rapid eye movement’ sleep.This progressive phase of sleep moves from ‘dozing’ to near full physical shutdown. NREM sleep has 3 sub-sets.
Phase 1 NREM is when wakefulness decreases and the brain goes from alpha wave to theta wave transmissions, each decreasing in amplitude and in-turn reducing alertness, think about it like turning down the dimmer switch on a light. Heart rate and respiration reduce. The individual will be aware of external noise but will largely be unable to respond.
Phase 2 NREM is characterised by two distinguishing phenomena: sleep spindles (short bursts of brain activity in the region of 12-14 Hz, lasting maybe half a second each, also known as sigma waves) and K-complexes (short negative high voltage peaks, followed by a slower positive complex, and then a final negative peak, with each complex lasting 1-2 minutes). Muscle activity reduces near nothing leading to many proposing this NREM sleep phase is when the body undergoes cognitive processing and processes memories from the day. Sleepers pass though this stage several times during the night, more time is spent in stage 2 sleep than in any other single stage, and it typically constitutes about 45%-50% of total sleep time for adults (or even more in young adults).
Phase 3 NREM is known as ‘deep sleep’, delta or slow-wave sleep. During this period the sleeper is even less responsive to the outside environment. Essentially cut off from the world and unaware of any sounds or other stimuli due to delta brain waves with a frequency as low as 0.5-4 Hz. Stage 3 sleep occurs in longer periods during the first half of the night, particularly during the first two sleep cycles, and represents around 15%-20% of total adult sleep time. Memory consolidation occurs during phase 3, and is also associated with sleep walking.
The second segment of sleep is REM or ‘rapid-eye movement’ sleep.
REM sleep occurs in 90-120 minute cycles during the night so roughly 3-4 phases a night. Brain
wave frequencies vary between alpha, theta and even beta waves (the same level as when the person is awake). Dreaming occurs during REM sleep as the brain experiences the release of ‘activator’ neurotransmitter acetylcholine and reduces the release of the inhibitory, ‘sleepy’ neurotransmitter serotonin. Despite this, the muscles of the body remain inactive as a protective mechanism to stop the body ‘acting out’ dreams. Unusual circumstances and places (such as being on holiday or living in a new strange environment) have been mentioned to be the reason why people spend more time in REM sleep as this is another phase where memory and task learning is processed. People are more likely to wake from REM sleep and it is proposed that if over-stimulated (being stressed and/or having too much information to process) the person may take the length of an entire sleep cycle (up to 2 hours) to get back to sleep after waking from REM sleep.
So this is what we know about sleep. In our next publication, we will discuss the factors that can influence these sleep cycles and what actually causes a bad nights sleep.