Good sleep is the source of our strength. During the night, our muscles are able to relax, cells and nerves need to regenerate and the brain needs to process what has been learned. Our sleep must follow a healthy rhythm to ensure that all of this functions properly: four sleep phases occur consecutively and together form sleep cycles which each last approximately 90 minutes. Then the next cycle begins. We go through four to five sleep cycles each night.
This phase begins when we close our eyes and usually only lasts a few minutes. We lie in bed, the light has been switched off and our body relaxes. Breathing slows down and the heart begins to beat more gently. We are still only in a light sleep at this stage and even minor disturbances can wake us. This is why we sleep particularly well if we go to bed in a dark and cool space and are not feeling stressed.
Light sleep phase
The light sleep phase lasts between 30 and 60 minutes and makes up the largest proportion of our night’s sleep. During this phase, our conscious mind switches off and we are no longer aware of our environment. Our body temperature falls, our heart rate, blood pressure and breathing rate slows down so that the strain on the heart and blood vessels is reduced. Superfluous knowledge is sifted out in the brain, nerve cells reconnect and key information is stored in our long-term memory.
Deep sleep phase
Deep sleep helps to regenerate the body and is extremely important for our memory. When the body is completely relaxed, it uses its energy to stimulate cell growth and to carry out necessary repairs. Newly acquired knowledge is particularly well memorised during the deep sleep phase. Deep sleep phases are the most intense during the first half of the night and become shorter as the morning draws nearer. They account for approximately 20 per cent of a night’s sleep.
REM stands for rapid eye moment, i.e. fast eye movements behind the eyelids which are typical during this sleep phase. This phase is also known as the dream phase because we perceive this phase to be the period in which we experience the most intense dreams. Our brain is just as active as it is when we are awake and our pulse rate and breathing rate are slightly elevated. Sleep researchers believe that dream sleep is particularly important for processing emotions, sensations and for internalising movement patterns.
The sleep hormone melatonin is responsible for making us feel sleepy during the evening and lower amounts are progressively secreted as morning approaches. The body is preparing to wake up. After a refreshing night’s sleep, we awaken gently from the final dream sleep phase. Daylight supports our natural circadian rhythm. As soon as our body is awake, its energy requirements increase We now need a hearty breakfast with fibre, protein and vitamins to tackle the day.