Post No.: 0390
Ever wondered what’s actually happening when you’re sleeping? It’s a more active process than you may realise…
When we sleep, we go through roughly 90-minute (60-100-minute) sleep cycles. The stages of sleep are stage one (feeling drowsy and relaxed), stage two (a slightly less light sleep when we may feel awake at this time but we’re actually asleep but don’t realise it, which can be a hazard when driving when tired), stage three (deep sleep, which is the hardest stage to wake up from) and REM (rapid eye movement sleep, which is the stage most associated with dreaming).
Stages two and three are ‘slow wave’ sleep stages. A typical sleep cycle goes through stages one, two, three, two, REM, and repeat – with later cycles having a longer REM duration.
In more detail, we start off awake, then move into light sleep (stages one and two), which is thought to cleanse our minds of the memories we don’t need. We receive vast amounts of information during the day and a lot of it isn’t considered important so this cements in place the memories that are considered important. If light sleep (which typically lasts ~20 minutes long) is constantly disrupted, we can really struggle to remember what happened during the previous day and become disoriented.
We then enter deep sleep (stage three, or formerly stages three and four), which involves the release of growth hormones, the repair of bodily damage and long-term memory solidification. If we don’t get enough deep sleep then it can increase our anxiety levels. It’s really difficult to wake someone up during deep sleep (which typically lasts ~60 minutes for the first cycle, getting progressively shorter during the following cycles until this phase is skipped completely in later cycles) but if deep sleep is constantly disrupted, people can become very unhealthy very quickly. Deep sleep is the time when sleepwalking, sleep talking and night terrors can occur.
Next we re-enter back through light sleep but then after that drift into REM sleep (which typically lasts ~5-40 minutes long, getting generally longer as the night wears on). Neurological-activity-wise, this stage is close to being awake but is accompanied with a low muscle tone throughout the body i.e. the body is effectively paralysed (unless REM sleep disordered). This is the stage when we do most of our dreaming. Some people may have experienced sleep paralysis before. This is when they’ve woken up before the REM stage has been fully completed, and they cannot move or speak but are conscious of their surroundings, which can feel quite scary. More rarely, such as with those who have narcolepsy, people may experience it as they’re beginning to fall asleep.
We always dream during REM sleep (apart from some stroke victims) and sometimes during NREM (non-REM) sleep too. So we all normally have several dreams every night but simply seldom remember them, or most of them, when the morning comes, hence we think we dream far less than we do. Dreams actually happen in real time (e.g. 5 minutes in REM will be described with 5 minutes of action), despite one of those myths. It might seem like much happens within a short time in our dreams but it’s probably like a 2-hour movie (chronological time) may cover a story that spans many days (narration time) and on top of that we can perceive time flying or slowing due to our subjective perceptions (emotional time).
NREM dreams tend to be more negative, they occur usually near the end of the sleep/in the mornings and occur far less frequently than REM dreams, which tend to be more positive or neutral. NREM dreams involve seemingly random fragmented thoughts, single words/concepts and lack a strong sense of a story line; unlike REM dreams, which seem to be very story-like. There is often increased blood flow to the genitals/arousal during REM too. Parts of the prefrontal cortex, which is involved in impulse control, are deactivated whilst REM dreaming too, hence we can often dream of doing things we wouldn’t ever normally imagine or do when awake!
Normally, by the time the first dream has finished, about 90-120 minutes will have elapsed (the first cycle is normally the longest). Generally, early in the night, deep sleep is longer but REM is shorter, and later in the night, deep sleep is shorter and REM is longer. Deep sleep is almost exactly the opposite of REM – in deep sleep, the brain is far more dormant and you’re cocooned away from reality (but body movements are possible); whereas during REM sleep – the brain is actually close to wakefulness and is highly active (but body movements are usually not possible). Non-dream sleep involves only localised brain activities, whilst REM sleep and being awake involves globally-integrated brain activities across wide regions of the brain.
That oscillating sleep cycle is then repeated several times throughout the night. Of course, all the above applies to those without specific sleep disorders. One may also experience some ‘brief awakenings’ during the night but won’t remember them, or more rarely we can dream of waking up or being awake but they’re ‘false awakenings’. Our perception of time is generally quite good while we’re sleeping, in the sense that we often wake up just before our alarm goes off.
Now in an ideal world, we’d just get up when our body feels ready to rather than use an alarm. But modern life is strictly timed and many of us need an alarm. However, it’s best not to use the snooze function if so because any sleep you could get inbetween these alarm calls will not be of a high quality – so simply set your alarm to the absolute latest time you must get up, then obviously get up at that time! If you ever feel ready to get up a bit earlier than this alarm time then get up earlier. (We probably shouldn’t be looking at designing products that make us wake up when we’re not ready to, as much as designing products or procedures that somehow make us go to bed in good time so that we’ll naturally feel ready to get up at the time we need to. Post No.: 0350 looked at good bedtime routines and practices.)
It’s totally fine to wake up from a dream or, as often happens, immediately afterwards – but waking up during deep sleep can make you feel awful (if you can help it that is). A 10-30-minute or 90-minute nap is therefore better than a 60-minute nap. (Here, it’s useful to set an alarm if you don’t want to sleep in during a nap. Or you could perhaps try drinking tea or coffee just before you nap so that the caffeine kicks in ~25 minutes later when you wake up?)
Preferably, one should just get enough sleep each night to not ever need a daytime nap, but if one doesn’t get that – and lots of us don’t in our modern lives – then a daytime nap is better than no nap if we feel tired in the day. We can only make up for a little bit of sleep debt on the weekends. Therefore napping can be much better than being sleep deprived during the weekdays. Some argue that it actually appears to be built into the human circadian rhythm to feel tired around 1 or 2pm, or 6-7 hours after you wake up in the mornings; although your working hours might not allow you to nap during these optimum times.
Apparently, even with only a 6-minute nap, you’re still getting huge benefits in terms of focusing, feeling refreshed, feeling in a better mood, remembering material better and so on. Even if you cannot manage to nap – lying down with the intention of napping can help result in a healthy reduction in blood pressure, even though you won’t get all of the other benefits of a proper nap or sleep. Be advised that a heavy lunch/meal can make you feel soporific or bring about a big ‘sugar crash’ afterwards, hence what you eat and drink also has an effect on your alertness, concentration and therefore productivity levels.
If you’re trying to shift your body clock due to jet lag then you should try to only sleep during the night according to the time zone you’re trying to adjust to. But if you really need a nap then make sure you don’t end up napping to the point you’ll no longer feel tired when night time comes.
Now hypnosis is not a form of sleep – during hypnosis, one is neurologically always closer to being awake than asleep. I’ve personally never been hypnotised before (or maybe that was what I was hypnotised to think(?!) :O) but people describe the experience of being hypnotised as being aware of what’s happening yet not being in control. They may not realise what they’re doing or remember what they had done under hypnosis yet they’re aware during the experience. Or they can remember an event but only if reminded of it. Whilst hypnotised, people are (even more!) suggestible and inhibitions are loosened but apparently (according to hypnotists!) no one can be made to do something that they ultimately don’t want to do. Well a person apparently cannot be hypnotised unless they want to be hypnotised in the first place, and, if so, then they will arguably ultimately still be responsible for their actions.
Those susceptible to being hypnotised tend to experience dreams that are more vivid, colourful, pleasant, exciting and bizarre (which in turn makes them more memorable), and these people are more likely to use their dreams as sources of creative inspiration, insight and meaning, such as interpreting them as paranormal clues about future events and so forth. (Of course this doesn’t mean that they actually have clairvoyant powers, as evident when their predictions are put under proper, independent, scientific scrutiny.) They also tend to be more able to take control of their dreams (lucid dreams).
Lucid dreaming is when you’re aware that you’re currently dreaming, and in some cases therefore able to control your dreams. If you want to try to experience a lucid dream – try to imagine your perfect dream just before you fall asleep and get into the habit of doing a lot of ‘reality testing’, as in testing to see whether you’re currently dreaming or not (e.g. try looking into a mirror (which should look blurry in a dream), levitating, turning on the lights (the illumination levels shouldn’t change) or checking the numerals on your watch (which again should look blurry)). Sleep interruption and playing video games can increase the likelihood of having a lucid dream for some. When you know you’re in a lucid dream, take it easy because excitement can wake you up. If you feel a lucid dream is about to end, try moving, spinning or rubbing your hands – the sense of movement may help you remain in the dream and contradict the fact that you’re just lying in bed. Lucid dreams are very difficult to achieve and few people regularly manage it though.
I’ll be covering dreams more directly in future posts on the topic of sleep. For now, I’m off for a little nap…
Woof. I tend to dream of chasing things – squirrels, sheep, cars, sticks, balls and strangely cheese.