A special state of rest

Which sleep stages are crucial for restorative sleep?

Good, restorative sleep consists of several stages: falling asleep, light sleep, deep sleep and the REM stage.

During falling asleep, pulse and breathing slow down and faint sounds are no longer perceived.

Light sleep is characterised by a reduction in muscle tone and spontaneous muscle twitches, because the muscles and the brain do not settle at the same pace.

Deep sleep is a period of physical regeneration: growth hormones are released, breathing and heart rate slow down. Typical sleepers spend about 20% of the night in deep sleep.

In the REM stage ("Rapid Eye Movement") people dream; the eyes move rapidly back and forth and emotions and dreams are processed. Pulse, breathing, brain activity and blood pressure increase. Waking from this stage often leaves vivid memory of the dream.

Over the course of the night, the particularly restorative deep sleep phases decrease while light sleep phases, during which we are more easily disturbed by external influences, increase.

Which factors affect sleep quality?

Sleep quality is influenced by internal factors (our psychological state, behaviour, illnesses) and external factors (noise, lighting conditions, the bedroom and bed climate). For example, negative thoughts, stress, anxiety or anger can trigger physical reactions that put the body on alert and prevent restorative sleep.

An American study also shows that a balanced diet plays an important role: too little fibre, too much sugar and too many saturated fats can adversely affect sleep.

How does light affect sleep?

The short‑wave blue light from electronic devices suppresses the release of the sleep‑promoting hormone melatonin and thus prevents you from winding down and sleeping restfully.

US sleep physicians have also found that brightness during sleep not only impairs sleep itself but also increases the risk of diabetes and heart disease. The body naturally knows when it is time to sleep from the cycle of darkness and light: if it never gets truly dark, the body lacks a decisive signal. It cannot fully recover, which can lead to impaired glucose and cardiovascular regulation.

When is the best time to fall asleep?

The best time to go to bed depends on your individual sleep need and your daily rhythm. Most adults need between seven and nine hours of sleep per night. It is ideal to go to bed and get up at roughly the same times to support your natural biorhythm.

A useful rule of thumb: count backwards from the time you want to get up – if you need to get up at 6:30, you should ideally go to bed between 21:30 and 23:00. Make sure you relax in the evening in good time to be able to fall asleep well.

In general, however, the best time to go to bed is between 22:00 and 23:00. This was shown in a study from England. Going to bed earlier or later can mean your internal clock cannot set correctly.

How does sleep quality affect mental performance?

Recent studies have shown that it is not so much the number of hours slept, but the quality of sleep that determines whether a person sleeps restfully. Only those who have restorative sleep will feel the positive effects on mental performance and the whole organism. Sleep is a special state of rest: it ensures that our energy balance is replenished night after night.

Typically, brain performance becomes exhausted after about 14 to 16 hours. The brain processes an enormous amount of information and sensory impressions, and therefore a recovery phase — namely sleep — is required. During sleep countless physical and mental repair and regeneration processes take place in our body.

PD Dr. med. Marc Spielmanns, Medical Director (Zürcher RehaZentren l Klinik Wald), Chief Physician Pulmonary Rehabilitation (Zürcher RehaZentren l Klinik Wald and Davos), Head of the Centre for Sleep Medicine explains: “Information, events and impressions collected during the day are transferred during sleep from a ‘temporary store’ (hippocampus) to the ‘hard drive’ (neocortex). However, this essentially only happens during sleep, because input processing in the temporary store and encoding into long‑term memory cannot operate at the same time in humans.”

In this way certain storage spaces in the brain are cleared, which we need again during the day to deal with other content. A British study by the Sleep Research Centre at Loughborough University in Leicestershire found that women's brains are wired more complexly than men's and that, for this reason, women on average require 20 minutes more sleep. When we sleep, our immune system also works at full capacity: it detects harmful intruders and tries to neutralise them.

Dreamy sleep: best tips for a restorative night

• Because the sleep hormone melatonin is only produced in darkness, dim the lights in the living area in the evening and darken the bedroom. If this is not possible, e.g. in a hotel, use a sleep mask. If you need to get up at night, use a dim light source so you do not fully wake up.
• These foods have a positive effect on sleep: dairy products, fish, nuts, oats and bananas. They contain tryptophan, magnesium and B vitamins, stimulate the production of the sleep‑promoting neurotransmitter serotonin and support sleep quality.
• Herbs such as hops or lemon balm support healthy sleep. Put two teaspoons of lemon balm leaves in a cup three times a day, pour hot water over them and drink slowly and relaxed. For acute insomnia, pour three teaspoons of lemon balm leaves with a cup of hot water, let steep for ten minutes and drink.
• An evening walk helps you sleep better: regular physical activity promotes deep sleep phases. However, highly circulatory exercise sessions, such as cardio training, should be avoided immediately before going to bed.
• Switch on the blue light filter of your smartphone, tablet or laptop from early evening to avoid blue tones in the light spectrum and to support melatonin production.
• If there are disturbing environmental noises, use earplugs: they reduce the sound level that reaches the eardrum. Pleasant sounds, such as soft music or calming sounds like the roar of waves, can also help to mask unfamiliar and disturbing noises.
• Soothing rituals before bedtime prepare you for restorative sleep. Take a warm bath, do relaxing yoga exercises or drink a calming tea.
• With the right pillow and a comfortable mattress you can avoid tension and improve your sleep quality. A good pillow adapts ideally to the natural shape of your body and thus relieves your cervical spine.
• Pay attention to the correct bedroom temperature. Ideally, you sleep at an ambient temperature of about 17 to 18°C. This allows the body to maintain its normal body temperature without effort.
• It is advisable to go to bed and get up at approximately the same time. Even at weekends and on holiday it is better not to deviate too much from this rule. If you want to change an irregular sleep rhythm, do so gradually and continuously, not abruptly.
• When you get up, try to get as much natural light as possible. That wakes the body and improves mood. Morning exercise outdoors is best — it increases energy and mobility in the morning.
• If worries or fears steal your sleep, meditation, breathing and relaxation exercises can help.

With these tips and tricks you are well equipped for consistently better sleep!