The importance of sleep for health: risks and dangers of sleep deprivation

Sleep accounts for around one third of our lives. Far more than simply a period of rest, it is a physiological process that is essential for our survival. Total sleep deprivation can lead to death within a few weeks.

Recent scientific studies show direct links between sleep quality and major serious diseases, including cancer and cardiovascular disease.

Yet our lifestyles and excessive screen exposure are progressively reducing the amount of sleep we get. A French study (INSVMGEN) measured an average loss of 90 minutes of sleep per night over the past fifty years.

Before looking at solutions, it is important to distinguish between simple sleep deprivation and actual sleep disorders.

If you suffer from insomnia, repeated nighttime awakenings or other chronic sleep disturbances, you can also read our complete guide to sleep disorders, their causes and treatments.

In this article, we take a closer look at the dangers of sleep deprivation and practical solutions for getting restorative sleep.

What is sleep? Definition and sleep cycles

Sleep is a state characterized by a loss of consciousness and reduced muscle tone and sensory sensitivity, as opposed to wakefulness.

It occurs in several cycles lasting 1 to 2 hours, comprising two main phases:

Deep non-REM sleep

After falling asleep and a short period of light sleep, the body enters deep non-REM sleep. This phase is characterized by an overall slowdown in muscular, cardiac, sensory and brain activity. It is the most restorative phase for the body.

REM sleep

REM sleep (Rapid Eye Movement sleep) is characterized by brain activity similar to wakefulness despite very low muscle tone. It is the main stage in which dreams occur and plays an essential role in memory consolidation and emotional regulation.

As the night progresses, the proportion of REM sleep gradually increases. As we age, the depth of non-REM sleep and the duration of REM sleep decrease, which partly explains why older adults sleep less deeply.

Napping: a restorative mini sleep cycle

Common among young children, napping remains beneficial throughout life. For adults, a short 15- to 20-minute nap consisting of light sleep is enough to restore alertness and reduce fatigue without making it difficult to wake up. Beyond this duration, there is a risk of entering deep sleep and waking up feeling groggy.

How many hours of sleep do you need? Sleep requirements by age

Sleep requirements vary between individuals, although these variations remain limited (around ±10% of average requirements).

Santé publique France recommends the following sleep durations:

Did you know? In France, one in two adults reports disrupted sleep, and nearly one third of the population has a chronic sleep deficit.

This sleep deficit is more pronounced in women than in men.

Most adults need 7 to 9 hours of sleep. Waking up feeling rested without an alarm clock is the best indicator.

Sleep regularity: a key factor that is often underestimated

It is not only the duration of sleep that matters, but also the regularity of your sleep schedule.

A British study involving more than 60,000 people followed over several years (Windred et al., 2023) found that greater sleep regularity was associated with:

• A 20% to 48% reduction in the risk of all-cause mortality
• A 16% to 39% reduction in the risk of cancer mortality
• A 22% to 57% reduction in the risk of cardiometabolic mortality

The body perceives changes in sleep schedules as a source of stress. It is recommended to keep variations in bedtime and wake-up time within one hour.

This impact is even greater in children and teenagers, whose biological rhythms are more sensitive to disruption.

What are the dangers of sleep deprivation?

Chronic sleep deprivation is associated with many serious health conditions:

• Weakened immune system
• Increased risk of cancer
• Cardiovascular and metabolic diseases (diabetes, obesity)
• Cognitive impairment, memory loss and reduced concentration
• Depression, anxiety and emotional dysregulation
• Reduced life expectancy

How can you improve your sleep? Natural and science-backed solutions

It is important to distinguish between solutions that help you fall asleep and those that improve sleep depth.

1. Helping you fall asleep: the role of melatonin

Melatonin is the hormone involved in falling asleep.

Its secretion is triggered by decreasing light levels at the end of the day. Artificial light from screens (smartphones, tablets, TVs) disrupts this natural mechanism by delaying the melatonin peak.

To make it easier to fall asleep:

• Dim the lights at least 30 to 60 minutes before bedtime
• Avoid screens during the same period
• Use a sleep mask if there is residual light exposure
• For jet lag or occasional stress: melatonin supplementation (1.9 mg/day for adults)

If difficulties persist for several weeks despite good sleep habits, you may be experiencing an actual sleep disorder.

We explain the different types of sleep disorders, their symptoms and available treatments in our dedicated article.

2. Improving sleep depth: physical activity, comfort and serotonin

Several scientific studies confirm that at least 30 minutes of daily physical activity (even divided into three 10-minute sessions) significantly improves all sleep parameters:

• Falling asleep
• Sleep depth
• Sleep duration.

For bedroom comfort, a cool room with a warm blanket provides an ideal environment, as lowering body temperature promotes deep sleep.

For stress management and deep sleep quality, serotonin (5-HT) plays a central role. Three micronutrients are essential for its synthesis:

• Magnesium
• Tryptophan
• Vitamin B6

Adaptogenic and calming plants (lemon balm, chamomile, passionflower, ashwagandha) also have evidence supporting their effectiveness in reducing stress and improving sleep quality.

Sleep in children and teenagers: a public health priority

Children and teenagers are even more sensitive to sleep deprivation than adults.

The presence of screens in bedrooms disrupts bedtime routines and generates nervous overstimulation that is incompatible with falling asleep peacefully.

Priorities for children and teenagers:

• Establish a calming bedtime routine (bath, reading, soft music)
• Avoid screens for at least 1 hour before lights out
• Maintain consistent bedtimes and wake-up times, including at weekends
• Encourage daily physical activity
• Magnesium can be used at appropriate pediatric dosages
• Any other solution (melatonin, herbal remedies) should be approved by a doctor
  

Conclusion: make sleep a priority

Sleep is not a waste of time: it is an essential investment in your physical and mental health and longevity.

At a time when screens dominate our evenings and chronic stress has become part of everyday life, getting enough regular sleep is one of the most effective preventive measures for maintaining long-term well-being.

There are many solutions, and they are often complementary: good sleep hygiene, regular physical activity, a balanced diet, as well as certain micronutrients or plants whose effectiveness is now well documented.

When these measures are not enough, it is important to consult a healthcare professional to identify any potential underlying cause.

If you would like to go further, we have brought together in one collection the Argalys dietary supplements specifically formulated to support stress management, help you fall asleep or support sleep quality. You can discover them here: Stress & Sleep Collection.

References & sources

1. Windred DP et al. (2024). Sleep regularity is a stronger predictor of mortality risk than sleep duration: A prospective cohort study. Sleep, 47(1), zsad253. https://doi.org/10.1093/sleep/zsad253

2. Gardiner PM, Kinnafick FE, Breen KC, Hartescu I. (2026). Physical Activity as a Tool to Improve Sleep Quality for Secure Psychiatric Inpatients: A Feasibility Study. J Sleep Res. Feb 2026. PMID: 40369847.

3. Hartescu I, Morgan K, Stevinson CD. (2015). Increased physical activity improves sleep and mood outcomes in inactive people with insomnia: a randomized controlled trial. J Sleep Res. https://doi.org/10.1111/jsr.12297