The sleep
Sleep is an active cyclic brain process ( REM phase and NREM phase) absolutely essential for maintaining general health.
During sleep, numerous processes useful for “central nervous recharge” and “physical recovery” are activated and facilitated; despite being characterized by immobility, reduced interaction with the environment and sensory-motor isolation, sleep is still responsible for the development of numerous brain processes.
Broadly speaking, it is possible to define that sleep reduces cerebral metabolism during the NREM phase and increases it during the REM phase; this alternation of the two phases determines an oscillation of central hyper and hypo activation in constant evolution and influenced by numerous neuro-endocrine factors. The hormonal axis that regulates sleep-wakefulness is also determined by: general stress , activities carried out in the evening, evening nutrition and other components of a psychological nature.
Influence of evening nutrition on sleep
Evening nutrition, both in quantitative and qualitative terms, can favor or make it difficult to initiate and maintain sleep.
Foods , and the nutrients they contain, interfere (in a more or less important way) in hormonal production and endocrine regulation ; moreover, the excessive use of the digestive system significantly penalizes the activation and quality of sleep itself. From a biochemical point of view, it has been amply demonstrated that some nutritional molecules determine the secretion of sleep-promoting mediators, while others perform the opposite function; among the hormones that promote sleep we mention:
- Melatonin
- Serotonin
On the contrary, among the molecules that make it more difficult we mention:
- Dopamine
- Adrenaline
- Norepinephrine
Having said that, it is obvious that pro-hypnic foods (i.e. foods that promote sleep) mainly supply molecules that are precursors and/or promote the synthesis of melatonin and serotonin. Fundamental groups:
- Foods containing tryptophan , an essential amino acid which in turn stimulates the production of melatonin and serotonin; it is contained in:
- Milk and cheese
- Meat and fish
- Egg
- Beans , chickpeas , broad beans , lentils , peas , peanuts
- Hazelnuts , almonds
- Whole Wheat
- Bananas , avocados , pineapples
- Spinach
- Foods containing complex carbohydrates , polymeric macronutrients which stimulate the pancreas to produce insulin , a hormone which favors the availability of tryptophan; complex glucids are contained above all in cereals and derivatives , potatoes and chestnuts .
- Foods that contain good quantities of Thiamine (vit B1, contained above all in cereals and legumes ) and Pyridoxine ( vit B6 , almost ubiquitous) as essential components for the biosynthesis of serotonin. NB: SIMPLE carbohydrates have a negative effect on the bioavailability of Pyridoxine.
- Foods that contain calcium and magnesium are also INDIRECTLY involved , the lack of which negatively affects sleep cycles.
Milk before sleep
Having an approximate view of the interaction between nutrition and the initiation and/or maintenance of sleep, it is now possible to evaluate more objectively the hypnic potential of milk consumed in the evening.
We begin by stating that:
- tryptophan, pyridoxine and calcium, although present in cow’s milk (the one most consumed) could also be ingested through the consumption of numerous foods; among other things, to be precise, drinking cow’s milk in the evening hours does NOT introduce significant quantities of thiamine, magnesium and complex carbohydrates , which are instead useful for promoting better quality sleep.
That said, it seems obvious that the habit of drinking milk in the evening in order to improve the quality of sleep (or even prevent insomnia ) has NO biochemical basis; in other words, from a nutritional point of view, a glass of milk before bed has a hypnotic efficacy similar or even lower than that of a plate of “beans all’uccelletto”. It is true that psychology probably plays a decisive role; some specialists attribute to warm milk before sleep a regressive potential which evokes infantile sensations and emotions responsible for a profound psychic relaxation… which has nothing to do with tryptophan.
In conclusion, drinking milk in the evening does NOT directly improve the quality of sleep, or rather, no more than other foods; an obvious objection could be that: drinking hot milk, unlike eating many other foods, doesn’t involve too much digestion … False! Cow’s milk, despite being a liquid food , certainly does not stand out for its easy digestibility. In fact, taking lactose tolerance for granted ( and avoiding the formation of lactulose with heat), the protein content of cow’s milk determines a sort of REBOUND effecton stomach acidity. It promotes a transitory increase in gastric pH following the DILUTION of digestive juices but subsequently, thanks to the proteins contained in it, it significantly stimulates the production of pepsinogen and hydrochloric acid; obviously, all this happens during sleep, when both stomach acidity and the tendency to gastroesophageal reflux (facilitated by the supine position) are not perceived. Therefore, although it may represent an indispensable habit, it is possible to state with certainty that drinking milk before bedtime is completely NOT RECOMMENDED for gastro-sensitive subjects or those suffering from other disorders of the upper digestive tract .
Matter of taste or drug addiction?
On the basis of some researches, the poor digestion of the proteins contained in cow’s milk would be responsible for the maintenance of numerous pathologies of the central nervous system ; the partial degradation of the aforementioned proteins would determine the entry (through the intestinal mucosa ) of peptides composed of 7-15 amino acids defined as ” opioids ” or “caseo-morphines”. It seems that these macromolecules (if present in relevant quantities) ALSO manage to cross the blood-brain barrier to interact with some opioid receptors of the nervous systemcentral; through this mechanism, caseo-morphines would hinder the uptake processes of melatonin and serotonin, and would cause neuro-psychiatric modifications such as addiction and behavioral alterations. On the basis of these results [Ledochowski 1998 – Lecks 1986 – Kaplan 1989 – Kahn 1985 – Kahn 1988 – Kahn 1989 – Hanninen 1999], it would be possible to define that drinking milk before sleep, in addition to not conferring any benefit, could lead to of sleep-wake cycles.
Readers should not take this research as “gold standard” or the discovery of the century; remember that the amino acids contained in milk proteins they are the same nutrients contained in all foods; moreover, how is it possible to determine whether these caseo-morphines actually derive from the intestinal lumen and were not intermediate metabolites of some other physiological or pathological process? Were the intestinal mucosa of the research samples intact? What is the age of the group studied (it is known that the intestinal permeability of children is much higher than that of adults)? What underlying neuro-psychiatric conditions related to the subjects? These are all questions whose answers would determine the reliability or otherwise of the above results; personally, I suggest the careful reading of the works and the independent evaluation of the conclusions reported by the authors.
