It’s likely that you’ve heard that we sleep in cycles, but what does this actually mean? We took a closer look at what really goes on in your mind when you snooze at night.
What happens when we sleep?
On the surface, it might look like nothing takes place when we drift off to sleep. But the truth is, as we rest after a long day our brains and bodies are busy repairing and restoring themselves. From light sleep to dreaming and deep sleep, the brain goes through five different sleep stages or cycles. These sleep cycles are known as are known as REM and non-REM sleep and normally last for around 10 to 90 minutes before being repeated several times each night.
What are the different stages of sleep?
As we fall into slumber, we enter four stages of non-REM sleep. Stage one is the light sleep state between being awake and actually falling asleep. This progresses onto stage two when we become less aware of our surroundings and begin to sleep. Our body temperature drops whilst our breathing and heart rate stay steady. The deepest and most revitalising stages of sleep are stages three and four. During these stages our breathing gets slower, our muscles relax and blood pressure drops. In addition, our energy levels are restored, our tissues grow and repair themselves and essential growth hormones are released to develop our muscles. We spend most of the time we are asleep in the Non-REM stages.
What happens after Non-REM sleep?
Following non-REM sleep, we enter the fifth sleeping stage – REM. This usually happens 90 minutes after we first fall asleep and normally lasts for 10 minutes. After this period of REM sleep, the cycle starts over again at stage one. Each REM stage gets longer as we stay asleep with the final one often lasting up to an hour.
What is REM sleep?
Rapid eye movement sleep or REM is so-called because during this stage, your eyes dart in different directions. This doesn’t occur during non-REM sleep. The brain is more active and breathing and heart rate become quicker. Since the brain is active, there’s a chance you will have vivid or intense dreams. We usually only spend up to a quarter of our time asleep in this stage.