What makes a good night’s sleep?

Good sleep is a topic that is often neglected, but it is a very important aspect of our everyday life. Sleep has been extensively studied and affects our quality of life in many ways — be it our efficiency at work, our endurance when it comes to daily tasks, or the prevention of diseases and maintenance of mental health, just to name a few.

Given the increase in the prevalence of sleep problems in many countries, we have decided to dedicate an article to this topic that summarizes evidence-based advice that can help you to improve the quality of your sleep without having to get a doctor’s prescription.

The advice encompasses topics such as ventilation and temperature, noise, the level of darkness, food, pharmaceutical drugs, mind relaxation, exercise, and helpful bedtime routines. Curious? Read more to find out how to address sleep problems in a natural way.

Sleep is essential to our health
It strongly influences our capacity to recover both mentally and physically, allows us to store memories, influences our mood, and promotes "growing" in children. It basically impacts every aspect of our life by affecting the way we think, learn, behave, feel, and interact with others.

Poor sleep and sleep deprivation have been associated with cardiovascular and metabolic diseases, impaired mental capacity, and poor motor coordination. Specialists have shown that “healthy sleep” might be the best way to prevent Alzheimer’s disease and that there is a strong relationship between sleep and proper functioning of the immune system.

While sleep disorders and the impact of sleep on general health have been extensively studied, the conditions necessary for good sleep, often called “sleep hygiene,” is sometimes overlooked.

Many times, we prefer to look directly at pathology and label our sleeping problems as a disease. We turn too quickly to medication and skip the simple yet critical changes we could easily make to get better sleep.
Here are the essential rules for good sleep:

1. Sleep in well-ventilated rooms and air out your home frequently
During respiration, we take up oxygen from the air and release carbon dioxide (CO2). Sleeping in closed, small rooms or confined spaces leads to CO2 build-up.

When the concentration of CO2 reaches the limit of 1'000 ppm, a number of body functions such as thinking, coordination, and sleep become affected.

There are many devices on the market that monitor indoor air quality. These can be used to measure the amount of CO2 in bedrooms, offices, cars, and public spaces (e.g., restaurants). A CO2 level of over 2'000 ppm can lead to headaches, poor concentration, increased heart rate, and nausea. A level above 40'000 ppm can cause brain damage, comas, and even death (values established by the National Institute for Occupational Safety and Health).

2. Pay attention to room temperature, air humidity, and pollution
The conditions for good sleep are met when the body doesn’t have to regulate its own temperature, reaching what is called the “thermoneutrality state.” You can achieve this without wearing pyjamas at an environmental temperature of 86–90 o F (30–32 o C) or wearing pyjamas and covering yourself with at least one sheet at 61–66 o F (16–19 o C). Warm blankets may hinder your sleep during the summer, and having cold feet in the winter also makes falling asleep more difficult.

Sleeping in a warm and highly humid environment increases the frequency of wakefulness episodes while low humidity dries out and inflames the respiratory tract. Ideally, humidity in the bedroom should be between 40–60 %. To increase humidity, you can use a vaporizer or a humidifier, or simply place bowls of water near the heat sources. The common methods to decrease humidity include promoting airflow (ventilating) and using a dehumidifier or an air conditioner.

Air pollution (mostly associated with traffic) affects sleep by acting upon the central nervous system and the upper airways. This can lead to reduced oxygen levels in the blood, respiratory acidosis, and obstructive sleep apnea. Furthermore, air pollutants can also contain allergens that induce inflammation, which in turn affects sleep quality. Air pollution meters usually display the VOC value (volatile organic compounds).

3. Avoid noise, even if you don’t think it bothers you
Noises above 50dB will shorten your total sleeping time. Even if you think you have become accustomed to the constant sounds in your environment, your body still perceives these and reacts accordingly.

Low-frequency noises (e.g., road vehicles, aircraft, ventilation, and air-conditioning units) may also affect sleep quality by increasing the time it takes to fall asleep and causing you to feel tired in the morning.5

4. Turn off all sources of light
Sleep is governed by light. Our internal clock (a group of cells in the hypothalamus) receives the signals that the eye sends in the presence of darkness or light. In response, it then generates either a state of sleepiness (by increasing the production of melatonin) or alertness (by increasing body temperature and releasing various hormones).

During the night, when the eye detects the slightest source of light (e.g., TV or electric clocks) the production of melatonin is stopped and sleep is affected. Sleeping with a night-light, staying up late in front of the TV or computer screen, and using your phone have all been shown to interfere with sleep.

5. Are you electrosensitive?
There is still strong controversy among specialists regarding the impact of electromagnetic fields (physical fields produced by electrically charged objects) on the human body. Some strongly support the idea that Wi-Fi and exposure to cell phone signals lead to difficulties falling asleep6, changes in sleep patterns7, restless sleep, and tiredness in the morning. Others suggest that this might apply only to electrosensitive people, while still, other research studies show that electromagnetic fields have no impact whatsoever on sleep patterns.
6. Tell me what you eat and I’ll tell you how you’ll sleep
Even though there are numerous points of view regarding the type of foods that promote a good night’s sleep, these appear to be the most agreed-upon aspects:

• Avoid alcohol. Even if it might make you drowsy, it affects the quality of your sleep and you will end up waking up more often and not sleeping deeply.
• Avoid sugary beverages, fruits, and snacks before bed. These increase your energy level making it more difficult for you to fall asleep. When you finally drift off, the drop in blood sugar levels will wake you up again.
• Make sure your evening meal contains foods high in L-tryptophan (e.g., walnuts, pumpkin, beans and lentils, spirulina, spinach, soy, and broccoli). This amino acid increases the production of melatonin and serotonin and helps you to get a good night’s sleep.
• Try to have the last meal of the day no later than 6 pm (or 5 pm for people with weight problems).

7. Do you take any prescription or over-the-counter drugs? Read the patient information leaflet!

Drug producers are required to include information about how the medicine might negatively impact your well-being, even if the occurrence of the problem and its severity might differ from person to person.
Drugs that usually cause sleep problems, including beta-blockers, medicines for high blood pressure, hormones, steroids, some antidepressants and anxiolytics, drugs for asthma, allergies, and ADHD, and medications containing alcohol and caffeine (e.g., most of the over-the-counter medications for coughs and colds).

8. Include sports in your daily activity
If exercising right before bed prevents some people from falling asleep because of overstimulation, exercising in the morning or throughout the day definitely increases both the quality and duration of sleep.

A study conducted in 2014 showed that eight weeks of aerobic exercise can significantly increase sleep quality in middle-aged women while other studies have shown significant improvement in sleep quality in both men and women when a form of physical activity was performed regularly.

9. Clear your mind
As difficult as it might be, don’t bring your work life, your worries, or the memory of negative events with you to bed. Rumination (repetitively going over the same thought or problem) has been proven to create a negative mood that will impair your sleep.

Before going to bed, try meditation or mindfulness exercises. Autogenic training is also an easy-to-learn, beneficial method to promote mental and physical relaxation.

10. Set up a healthy bedtime routine
Establish a bedtime routine (e.g., reading, walks in nature, and/or meditation) and try to have consistent sleep-wake times (go to bed and wake up every day at the same time). These habits have been shown to improve sleep quality and reduce the amount of time it takes you to fall asleep. Significant improvements have been observed in children10, but studies show similar effects in adults and the elderly.
Most of the time, people are not aware of their habits and the activities they engage in during the hour before they go to sleep. Nevertheless, these have a significant impact on the quality of their night-time rest. For example, using smartphones in bed and being exposed to blue light has been associated with longer sleep latency, sleep disturbances, and decreased performance the next day.