Well, maybe not everything but here are some interesting things about sleep some people may not know. Sleep is not as simple as closing your eyes and losing consciousness for a few hours. There are two states of sleep: REM and non-REM (where REM stands for Rapid Eye Movement). NREM sleep has four stages and the sleep cycle moves from stages one to four of NREM sleep before entering REM sleep. This cycle then repeats.


Stage 1: The individual begins to fall asleep, lasting around five to ten minute. Eye and muscle movement begin to slow and the individual is easily awakened.

Stage 2: The individual enters light sleep, lasting around ten to twenty five minutes. Eye movement stops, heart rates slows, and body temperature decreases.

Stage 3: The individual begins deep sleep. No eye or muscle movement.

Stage 4: The individual is in deep sleep. Difficult to wake individual and if wakened, the individual will feel groggy and disorientated. Blood flow is directed away from the brain towards the muscle, restoring physical energy.

REM: Arms and legs paralysed, breathing shallow, rapid eye movement, vivid dreaming occurs and REM sleep refreshes the mind.

So what’s the significance? Well, deep sleep is achieved in stages three and four of NREM sleep. If you are wakened in stage one you tend to feel poorly rested. A small period of dreaming occurs at the end of the cycle in REM sleep. In general, a sleep cycle lasts around 90 minutes (65 minutes of NREM, 20 minutes of REM, followed by a final 5 minutes of NREM).

Sleep tips:

So what does all this mean? Using this knowledge (and some info I haven’t included yet), we can draw these conclusions, which I consider some tips on sleeping well.

  • You should try to plan your sleep so that you sleep for a duration that is a multiple of 90 minutes (length of a sleep cycle).
  • Sleep deprivation is from inadequate deep sleep (stages three and four); being woken in the middle of the night and sleeping late can limit your deep sleep.
  • Sleeping late/during the day is bad because your circadian rhythm (biological clock) is regulated by processes in the brain that distinguish between light and dark. At night, your body responds to the darkness by producing melatonin, a hormone that induces sleepiness. During the day, sunlight causes your brain to limit the production of melatonin. Your circadian rhythm gets disrupted by sleeping at inappropriate times and travelling through time zones.
  • Six hours of sleep is not enough – just because you can function on less sleep doesn’t mean that you are functioning optimally. Adults are recommended 7.5 to 9 hours sleep.
  • If you find it hard to wake up to your alarm, it’s most likely because you were woken during stage three or four (deep sleep). Refer back to the first tip to avoid this.
  • Sleep debt cannot be repaid in just a few instalments. It’s best to repay sleep debt in multiple instalments (one or two hours extra per night until the debt is over, rather than all five hours at once).
  • Apples are more effective than coffee at waking you up in the morning. Also, your body adjusts to caffeine so that over time, it becomes less effective so if you like drinking coffee to wake yourself, try not to drink it all the time or it loses its potency
  • Getting up straight away after you wake up is better for you than hitting snooze over and over

I think everyone knows enough about lucid dreaming already since the Inception craze. I think I might follow up this post with something about Inception later.