on June 26, 2026
Sleep is not a pause: it is an active biological state
We live in a society that tends to view sleep as time taken away from productivity. In reality, rest is one of the most active and essential biological processes for maintaining health.
During sleep, the brain continues to consume amounts of energy comparable to those during wakefulness, while profoundly altering its neurochemical and organizational functions.
We do not sleep to turn off the brain.
We sleep so that the brain can function.
Modern evidence shows that during rest, processes involved in metabolic regulation, neuronal plasticity, memory consolidation, immune control, and the maintenance of homeostasis are activated.
Sleep deprivation rapidly impairs attention, learning, decision-making abilities, emotional regulation, and cognitive performance.
Even a single night of sleep restriction has been associated with measurable changes in executive function and concentration.
The sleeping brain: memory, learning, and the glymphatic system
For a long time, it was thought that the brain simply reduced its activity during sleep.
Today we know that is not the case.
During sleep, a reorganization of the information collected during the day takes place.
The neural networks involved in memory are reactivated and consolidated, while some of the redundant information is eliminated.
This process allows for the optimization of the information load and prepares the brain for subsequent learning.
In recent years, the glymphatic system has gained interest, a functional network involved in the drainage of metabolites and proteins from brain tissue.
Experimental studies suggest that during deep sleep, the convective transport of cerebrospinal fluid increases, facilitating the removal of metabolic products, including protein aggregates such as beta-amyloid and tau.
Although the causal relationship with neurodegenerative diseases is still being studied, chronic sleep alterations are associated with a greater risk of cognitive decline.
Chronobiology: the biological time that governs metabolism
Sleep does not depend solely on the number of hours slept.
Our body functions through a sophisticated synchronization system called the circadian rhythm.
This system coordinates hormone production, body temperature, energy metabolism, immune function, digestive secretion, and sleep-wake cycles.
The main environmental synchronizer is light.
Evening light exposure, especially from electronic devices, can interfere with the signals that regulate the biological clock and delay the physiological preparation for sleep.
Diet, physical activity, and social schedules also participate in biological synchronization.
When lifestyles diverge from physiological rhythms, the phenomenon known as circadian misalignment increases, associated with poorer metabolic control, endocrine alterations, and poorer sleep quality.
Sleep stages and body recovery
Sleep is organized into cycles that repeat throughout the night.
Each cycle includes light sleep, deep sleep, and REM sleep.
The first cycles are generally richer in non-REM deep sleep, associated with physical recovery and homeostatic regulation.
The last hours of the night show a greater presence of REM sleep, involved in cognitive processes, emotional processing, and preparation for wakefulness.
Rather than chasing an absolute number of hours, the goal should be to promote continuity and quality of rest.
For most adults, the average requirement falls between 7 and 9 hours per night.
Sleep, immunity, and metabolism
Sleep has profound effects on the immune system.
During rest, coordinated variations of cytokines, hormones, and mediators involved in immune regulation are observed.
Chronic sleep restriction has been associated with increased cortisol, greater sympathetic activity, and reduced immune efficiency.
Energy metabolism is also strongly affected.
The reduction of sleep hours has been associated with alterations in ghrelin and leptin, hormones involved respectively in the regulation of hunger and satiety.
This can promote increased appetite, preference for highly energetic foods, and a greater risk of weight gain.
Nutrition and sleep: when to eat is as important as what to eat
The evening meal represents one of the main metabolic signals.
Hearty dinners, rich in saturated fats or consumed very late, can interfere with digestion and sleep quality.
Sleep nutrition focuses on moderate, digestible meals within a time window consistent with the circadian rhythm.
Particular interest is paid to nutrients involved in the synthesis of neurotransmitters.
Among these, tryptophan represents the main precursor of serotonin and subsequently melatonin.
Plant-based foods that contribute to tryptophan intake include legumes, whole grains, sesame seeds, sunflower seeds, spinach, lettuce, asparagus, pumpkin, mushrooms, banana, and pineapple.
The metabolic conversion also involves the availability of vitamin C, magnesium, and B vitamins.
Omega-3s also seem to participate in the neurobiological regulation of sleep through effects on neuronal function and cellular signaling.
Phytotherapy and physiological support of sleep
Phytotherapy can be part of a comprehensive approach focused on the physiology of sleep.
The goal is not to artificially induce sleep but to support the natural processes that promote relaxation and biological synchronization.
Among the most studied plants are valerian, traditionally used to promote relaxation and studied for possible effects on GABAergic regulation.
Passionflower has been evaluated for support of perceived sleep quality and the management of evening hyperarousal.
Lemon balm has been studied for its potential calming effect and support of sleep quality.
Chamomile shows biological activity attributed mainly to flavonoids and certain aromatic constituents.
Lavender and aromatherapy have been investigated especially in the context of the perception of relaxation and subjective sleep quality.
The available evidence is variable and does not replace the treatment of clinical conditions that require medical evaluation.
Melatonin, although not a plant, also represents one of the main physiological regulators of the circadian rhythm and is studied especially for the synchronization of the sleep-wake cycle.
Rest as a daily biological choice
Sleeping well does not simply mean falling asleep.
It means building the conditions during the day so that the nervous system can recognize the time for rest.
Exposure to natural light, regular physical activity, a diet consistent with biological rhythms, reduction of evening stimuli, contact with the outside environment, and decompression rituals represent tools that are often more powerful than any immediate solution.
Sleep is not the time that remains after the day.
It is the process that prepares the next day.
Bibliography
Walker MP. Why We Sleep. Scribner.
Xie L et al. Sleep drives metabolite clearance from the adult brain. Science. 2013.
Tononi G, Cirelli C. Sleep and synaptic homeostasis. Sleep Medicine Reviews. 2014.
Cappuccio FP et al. Sleep duration and cardiometabolic outcomes. Eur Heart J. 2011.
Taheri S et al. Short sleep duration associated with leptin and ghrelin. PLoS Med. 2004.
Riemann D et al. European guideline for insomnia. J Sleep Res. 2017.
Fernandez-San-Martin MI et al. Valerian for sleep. Sleep Med. 2010.
Miyasaka LS et al. Passiflora and sleep regulation. Phytother Res.
Chang AM et al. Evening use of light-emitting devices. PNAS. 2015.
Irwin MR. Sleep and inflammation. Nat Rev Immunol. 2019.
