

































Abstract: Young adults in the United States are increasingly a!ected by delayed sleep-wake phase disorder (DSPD), 
a prevalent circadian rhythm disorder that delays evening sleep and morning wake times relative to the solar cycle. 
Although medicinal supplements have shown to produce e!ective results on immediate sleep induction, they lack 
the ability to aid in regulation and maintenance of routine sleep schedules. Alternatively, a dietary method may 
be able to adjust the de"cits of supplements. A review of the literature on clinical nutrition and endocrinology 
suggests that dietary#alterations through the timed consumption of tryptophan-abundant whole cow’s milk may 
be an auxiliary option of improving sleep quality and morning alertness in individuals with DSPD. Studies on 
chrono-nutrition indicate that dietary components absorbed by the bloodstream can alter the circadian schedule 
of melatonin secretion from the pineal gland, and the timed consumption of tryptophan-abundant foods, such as 
whole cow’s milk, can consequently spike melatonin levels before a DSPD patient’s desired sleep time and promote 
circadian rhythm advancement. Based on the stated studies, this research proposes the Melatonin Intake through 
Lactalbumin (a-lac) Consumption (MILC) treatment, or the consistent, timed consumption of milk. $e MILC 
treatment may decrease a DSPD patient’s morning sleepiness on the basis that disordered, high-stressed, and sleep-
deprived individuals are susceptible to minimal changes in hormones because their bodies naturally attempt to 
attain homeostatic equilibrium. $e correlation between chrono-nutrition and dietary e!ectiveness is a novel idea, 
and testing is needed to quantify the optimal timings and ranges of dietary tryptophan that can produce a signi"cant 
e!ect on the sleep quality of a DSPD patient.#
 
Keywords: delayed sleep-wake phase disorder, chrono-nutrition, alpha-lactalbumin

Aisthesis      Volume 13,  202257

Enhancing Melatonin Secretion: !e Methodical Consumption of 
Tryptophan from Whole Cow’s Milk to Regulate Sleep Quality in 
Individuals Aged 18-30 with Delayed Sleep-Wake Phase Disorder

by Shraddha Patel

1. Introduction 
 Delayed sleep-wake phase disorder (DSPD) is 
a circadian rhythm disorder in which an individual 
lacks the ability to fall asleep within a socially 
acceptable time. $e symptoms of DSPD patients 
are variable based on their individual routines and 
biological predispositions for sleep disorders. Some 
display signs of insomnia while others struggle with 
sleep latency, or the time that it takes an individual 
to actively initiate sleep at night. On the other hand, 
some patients lack total sleep e%ciency timing, or 
the total percentage of time that individuals spend 
sleeping in bed. Others may have delayed sleep 
patterns because of unavoidable circumstances 
such as night shi&s and demanding responsibilities. 
Among all categories of patients and their symptoms, 
researchers have found that the greatest overarching 
problems are morning alertness, drowsiness, inability 
to focus, and decreased retention (Berendsen et al., 
2020).

 $is sleep disorder can be traced back to the 
sleep-inducing hormone, melatonin; its secretion 
from the pineal gland is a determinant of the 
consistency and extent of circadian o!set in sleep-
deprived individuals. $ose with delayed circadian 
schedules encounter 'uctuations in hormones, and, 
as a result, the pineal gland’s secretion of melatonin 
is unable to adjust to a regular, timely pattern. $e 
dim light melatonin onset (DLMO), or the timing of 
melatonin secretion patterns from the pineal gland, 
shi&s in accordance with an individual’s average 
delayed sleep schedule; at minimum, the DLMO shi& 
is 2 hours a&er the socially accepted sleep onset time 
(Micic et al., 2007). $is shi& determines the extent 
of correlation between DLMO and sleep timing, and 
with the large delay for DSPD patients, adjustment 
is necessary through external or exogenous factors 
such as light exposure or overall dietary intake.



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 Melatonin is only released by the pineal gland at 
night, but it can also be synthesized from the dietary 
intake of the essential amino acid, tryptophan. 
Tryptophan conversion can increase melatonin 
concentrations and induce sleep through the 
tryptophan–serotonin–melatonin pathway (Richard 
et al., 2009). Consumption of naturally high-
tryptophan foods or drinks may advance DLMO 
timings and increase melatonin secretion levels 
up to 6 hours a&er intake. If timed accurately, the 
high-tryptophan food can be used to enhance sleep 
quality in DSPD patients by accelerating melatonin 
secretion before the pineal gland starts its delayed 
release of melatonin. $rough this method, the 
increased melatonin levels can induce deeper sleep 
and enhance sleep quality in terms of morning 
alertness.
 One speci"c sleep inducing, high-tryptophan 
drink is whole cow’s milk; it has the highest 
tryptophan content of all milk types due to its alpha-
lactalbumin protein levels (Markus et al., 2000). Cow’s 
milk also contains nutrients, such as calcium and 
potassium, that work through alternative pathways 
to aid in sleep-induction. Although plant-based and 
other mammalian-milk types have other de"ning 
properties and nutritional contents, cow’s milk is 
largest in terms of tryptophan; it is also one of the 
highest produced milk types and is widely available 
to the public (Yamaguchi et al., 2014). $e newly 
proposed Melatonin Intake through Lactalbumin 
(a-lac) Consumption (MILC) treatment consists of 
DSPD patients intaking 1 cup of whole cow’s milk 
1-2 hours before their desired sleep time, which 
may improve their overall sleep health and morning 
functionality, even if their circadian schedule does 
not shi& times.
 
2. Delayed Sleep-Wake Phase Disorder and Phase 
Shi!ing  
 Because young, DSPD patients have speci"c 
di%culties in regulating their sleep and circadian 
rhythms to the socially acceptable times, research 
suggests that the best way to improve their sleep 
quality would be to manipulate endogenous factors 
by altering melatonin levels through the intake of 
tryptophan.  
 Chang et al. (2009) claimed that individuals 
with delayed sleep wake phase disorder have an 
o!set sleep episode later than desired, and this 

can lead to di%culty in morning functionality and 
struggles in awakening. $ey added that individuals 
have a specialized circadian schedule based on 
their health, age, and lifestyle, and a delay or shi& 
in sleep schedules based on solar cycles may lead to 
insu%cient and non-restorative sleep when it comes 
to duration and quality.  
 $ose with DSPD struggle in terms of long-
term physical and mental functionality rather than 
overall health, but the symptoms can di!er between 
geographical time zones, as countries have di!erent 
socially acceptable sleep timings. $ese di!erences 
create a wide range of sleep habits across the globe 
as determined by Krueger & Friedman (2009), who 
reasoned that individuals in the United States have 
an average sleep initiation time of 10 PM–12 AM 
and awaken at 7:00 AM. On the other hand, DSPD 
patients are generally unable to fall asleep before 2 
AM, and if their schedules permit, they don’t wake 
up until 11:00 AM–1:00 PM. $is wide distribution 
of sleep times can further be attributed to individual 
schedules and variable intensity of the disorder.  
 With age being crucial to the body’s ability to 
adjust to stimuli, researchers have performed studies 
to determine the prevalence of DSPD in the young 
adult age range. Berendsen et al. (2020) studied 
patients with DSPD aged 13-20 due to a 7-16% 
prevalence of circadian disorders within that age 
range. Micic et al. (2007) added to the validity of that 
"nding in their study about melatonin pro"les in 
DSPD patients. $ey determined that young adults 
between the ages of 20-30 have the lowest melatonin 
secretion of all other age ranges; researchers 
interpreted that DSPD patients fall within that age 
range due to the delayed hormonal secretory rates 
and high stress levels. Both studies concluded that 
DSPD patients who need the greatest amount of aid 
in resetting their circadian rhythm are young adults, 
and the age controls can be used to quantify the 
“normal” amount of melatonin secretion and sleep 
that an average individual should maintain.  
 Akerstedt & Gilberg (1986) measured the 
subjects’ daytime sleepiness through the EEG 
(electroencephalogram) power density analysis, a 
test that records brain activity and electrical signals 
through small sensors in the scalp. $e researchers 
found that individuals who were restricted to 
fewer hours of night sleep were increasingly prone 
to daytime sleepiness, and they required greater 



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Aisthesis      Volume 13,  202259

recovery time to return to a “normal” level of 
alertness. Although this test was conducted on 
healthy subjects, the results can be applied to DSPD 
patients who have increasingly restricted sleep 
schedules because of their consistent non-restorative 
sleep; thus, they tend to “crash” whenever they get the 
chance. $is crash is an e!ort to recover sleep loss as 
described by Akerstedt & Gilberg (1986). $ose with 
sleep loss need to recover minimum power density, 
or adequate frequencies and intensities of sleep 
waves, to restore su%cient energy from prior fatigue. 
Exhaustion from an incomplete sleep cycle can 
be carried over in individuals, and this can reduce 
attention in the morning or cause sleep crashing 
on o! days. $is extended sleep crash in healthy 
individuals is a homeostatic attempt to recover a 
percentage of the prior loss. DSPD patients generally 
have compounding sleep de"cits and the e!ects from 
time constraints can prevent normal homeostatic 
sleep recovery. Whenever patients “give in” to their 
homeostatic sleep struggles, then prior loss can be 
partially recovered through an excessively long sleep, 
usually during the weekends.  
 Chang et al. (2009) found that DSPD patients 
were going to bed nearly 29 minutes later on 
weekends and waking up 50 minutes later as 
compared to a regular weekday (p < 0.05). DSPD 
patients and healthy individuals had similar sleep 
e%ciency and latency when placed under unstressed 
conditions. $is "nding allowed them to shi& the 
focus of their study to sleep quality, melatonin 
rhythms, and general alertness because these aspects 
are highly variable in patients with sleep disorders. 
All three factors can be shi&ed through exogenous 
changes such as melatonin supplements, solar light 
cues, or bright light exposure. $is modi"cation can 
initiate the endogenous melatonin secreted from the 
pineal gland to realign and form a stable temporal 
relationship to obtain an optimal sleep-wake rhythm.  
 Although an exogenous shi& in circadian phase 
can occur through light therapy and photic stimuli, 
researchers are exploring dietary methods as an 
alternative. Richard et al. (2009) discussed that the 
hormone melatonin correlates with sleep based 
on its concentration, production, and secretion 
from the pineal gland during the dark phase of the 
solar cycle. An additional mechanism of melatonin 
production is through its synthetization from 
its essential amino acid precursor, tryptophan. 

Manipulating tryptophan levels could be used as 
a dietary alternative to supplements to increase 
melatonin levels and the induction of phase shi&s to 
improve sleep quality. Micic et al. (2015) emphasized 
that those with sleep disorders can utilize exogenous 
factors such as the tryptophan content in food to 
instigate melatonin production.  
 $e melatonin secretion of young adults can 
become o!set due to social times dependent on their 
age range, and the continuous shi&ing of circadian 
phases can lead to the formation of delayed sleep-wake 
phase disorder. Research suggests that manipulation 
of exogenous and endogenous stimuli can shi& sleep 
quality and establish a normal temporal rhythm, 
and the manipulation of melatonin through dietary 
means is crucial to understanding how to manage 
DSPD symptoms.

3. "e E#ects of Exogenous Factors on the 
Melatonin Synthesis Pathway  
 Because tryptophan is the sole precursor of 
melatonin, an increase in tryptophan intake may alter 
the overall melatonin pro"les and concentrations to 
boost mood and potentially increase sleep quality 
through phase shi&ing.  
 As previously mentioned, Micic et al. (2015) 
studied the nocturnal melatonin pro"les in patients 
with DSPD and healthy sleepers to determine 
how o!set circadian timing can contribute to the 
development of delayed sleep-wake phase disorder. 
$ey determined that there was a 2–6-hour delay 
in the circadian rhythms of the DSPD group as 
compared to healthy sleepers. However, the greatest 
determinant in sleep health between both types of 
sleepers was the initial burst of melatonin in the 
early part of the night and the melatonin production 
'uctuations throughout the night. 
 Shibui et al. (1999) established a positive 
correlation between sleep phase markers and 
melatonin phase markers. Whenever melatonin 
levels increase during the night, the individual enters 
a deeper state of sleep, and the lower the melatonin 
levels, the closer an individual is to an alert state. An 
average individual has peaks in melatonin secretion 
from the pineal gland between 2 AM and 4 AM, 
gradually decreasing a&erwards. However, a DSPD 
individual has melatonin peaks during morning 
sunrise hours, and if they have a morning time 
constraint to awaken for, their sleep cycle won’t 



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Aisthesis      Volume 13,  202260

be completed. Not only does this lead to excessive 
lethargy and decreased alertness from the high 
melatonin concentrations in the morning, but it can 
also add to the non-restorative sleep percentage. $is 
cycle can be combated by advancing the melatonin 
onset through exogenous factors that can increase 
melatonin production at a desired time.  
 Melatonin can be obtained through the intake 
and conversion of tryptophan, an essential amino 
acid that can only be obtained from food. Richard 
et al. (2009) stated that the recommended daily 
intake of tryptophan is 250-425 milligrams per day, 
and foods high in tryptophan are bene"cial for sleep 
regulation because they can adjust melatonin levels 
and diurnal rhythms through conversion. Once 
tryptophan enters the body through food intake, it 
can enter numerous pathways to create necessary 
building blocks and molecules in the body. One 
speci"c path, called the melatonin synthesis pathway, 
drives tryptophan to be converted into melatonin 
through a series of chemical reactions. 
 To determine the potential of diet-induced 
tryptophan as a treatment method for DSPD patients, 
researchers have attempted to use the amino acid to 
raise the serotonin and melatonin levels in the body, 
yielding positive changes in sleep quality through 
relaxation and sharpened morning alertness.  

4. Correlation Between the Trp:LNAA Ratio and 
the a-lac Content of Whole Cow’s Milk  
 Because tryptophan (Trp) is an essential amino 
acid, it must be derived from food and must compete 
with other large neutral amino acids (LNAA) to 
get accepted into a transporter on the blood brain 
barrier (BBB), a highly selective semipermeable 
membrane that controls what molecules enter 
the brain from the bloodstream. Once a molecule 
passes through the transporter, it will have a greater 
chance of undergoing catabolism and entering its 
various synthesis pathways. $is highly competitive 
transportation process between tryptophan and 
other amino acids in the body determines what 
molecule will have the greatest in'uence in the 
brain. If tryptophan has a greater concentration than 
other amino acids inside the BBB, then it is classi"ed 
as having a high Trp:LNAA ratio. $is ratio raises 
the chances of tryptophan being synthesized into 
melatonin, increasing the e%cacy of sleep regulation.

 Regarding the synthesis of melatonin in the 
brain, Markus et al. (2000) established that proteins 
and carbohydrates are both macromolecules that 
can release varying quantities of tryptophan, 
thus altering the ratio between amino acids. $e 
concentrations of these amino acids can determine 
the level of brain serotonin, stress management, 
depression, and mood. To understand the optimal 
e%ciency of raising tryptophan levels through 
serotonin synthesis, Richard et al. (2009) studied 
the interaction of amino acids in the blood brain 
barrier. Once ingested, nearly 95% of the tryptophan 
that enters the circulatory system is bound to 
albumin while the rest remains unbound. Unbound 
tryptophan has a high chance of entering the BBB, 
but the bound tryptophan also gets pulled towards 
the BBB transporter; therefore, it must compete with 
neutral amino acids in order to be accepted by the 
transporter. All competing amino acids take part 
in competitive inhibition to be transported across 
the barrier and contribute to the Trp:LNAA ratio 
gradient; the more tryptophan available to compete, 
the greater the chance that it will enter the BBB and 
continue its path towards serotonin synthesis.  
 Addressing tryptophan levels, Richard et al. 
(2009) emphasized that one of the best ways to 
increase tryptophan concentration in the brain can be 
through the increased consumption of carbohydrates 
and decreased consumption of proteins. $ese 
macromolecules do not immediately change the 
Trp:LNAA ratio, but rather contribute to the levels 
of amino acids circulating in the bloodstream that 
are available to compete. Speci"cally, carbohydrates 
decrease the LNAA concentrations and increase 
the tryptophan levels, while proteins increase the 
LNAA concentrations and decrease the tryptophan 
levels. Proteins can deplete plasma tryptophan 
concentrations and decrease the Trp:LNAA ratio 
through increased peptide chain formation from 
protein synthesis, and this produces a net increase 
in the LNAA concentrations. A balance of both 
macromolecules needs to be achieved for obtaining 
tryptophan (proteins) and converting tryptophan 
(carbohydrates) into serotonin. 
 Markus et al. (2000) narrowed down one notable 
exception to the CR-PP rule: alpha-lactalbumin 
(a-lac). A-lac is a whey protein that has qualities 
that are conducive to serotonin synthesis, and its 
tryptophan content could be able to overcome 



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Aisthesis      Volume 13,  202261

competitive transporter blocks, making it a key 
component#to enhance sleep quality; this protein has 
the highest tryptophan levels of all bovine proteins 
at around 4.8g/100g, and the researchers tested 
its success at raising the Trp:LNAA ratio despite it 
being categorized as a protein with high quantities 
of competing amino acids. Yamaguchi and Takai 
(2014) determined that a-lac constitutes nearly 
3.5% of the total proteins in bovine milk, and one 
cup of whole cow’s milk (237 mL) contains 284 
milligrams of alpha-lactalbumin and 100 milligrams 
of tryptophan. $ese quantities are relatively high, 
considering that one cup of milk nearly contains half 
of the daily recommended amount of tryptophan. 
 Zeng et al. (2014) found that milk intake can 
stimulate serotonergic activity and melatonin 
synthesis to induce enhanced sleep. Whole cow’s 
milk is enriched with omega-3, polyunsaturated 
fats, calcium, and potassium; these molecules can 
a!ect sleep based on the pathways that they enter, 
and the products they form in the bloodstream. 
High levels of omega-3 correlate with increased 
conversion of serotonin into melatonin. Similarly, 
polyunsaturated fatty acids are positively associated 
with increased sleep e%ciency and REM deep sleep. 
Calcium and potassium have the ability to promote 
sleep because of their role in the modulation of 
voltage-dependent channels that generate slow 
waves and sleep spindles. Slow waves occur in non-
rapid eye movement (NREM), stage 3 sleep, also 
known as deep, delta sleep, in which individuals are 
di%cult to awaken. $e deeper the sleep, the more 
substantial the restorative process in DSPD patients. 
In context to the overarching problem, milk has the 
components available to work on di!erent aspects of 
sleep; when consumed by a DSPD patient with sleep 
deprivation and excessive lethargy, the milk can 
enter pathways and synthesize hormones that can 
regulate a healthier circadian rhythm.  
 Markus et al. (2000) measured the extent to which 
mood, digestion, and stress levels were a!ected by 
a-lac intake in vulnerable individuals. When testing 
subjects with various intensities of stress tolerances, 
the low-stress control group received casein protein, 
a protein high in large neutral amino acids, while the 
high-stress experimental group received a-lac whey 
protein. Markus et al. (2000) gathered university 
students aged 17-34 as their optimal test subjects 
because of their high vulnerability to stress, while the 

control group consisted of low-stress students with a 
mean age of 20.9. $e highest prevalence of DSPD 
patients also fall within this age range, and many 
of them are considered high stress with regards to 
both circumstance and sleep health. Results from the 
researchers’ study indicated that the high-stressed, 
high-cortisol test subjects were exceptionally prone 
to the e!ects of alpha-lactalbumin in raising their 
plasma Trp:LNAA ratio; there was a statistically 
signi"cant 48% increase in the ratio for those who 
were on the a-lac diet as compared to the casein 
diet. $e experimental a-lac diet also boosted 
mood and reduced cortisol response in high stress 
(HS) individuals as compared to the low stress 
(LS) individuals when exposed to stressors. Before 
conducting the experiment, the HS group had greater 
serotonin breakdown, creating a rise in cortisol levels 
as a biological response to stress, and this catabolism 
led to depression. However, when raising tryptophan 
availability in the brain using a-lac, the HS group 
experienced a decrease in depressive moods because 
of greater serotonin synthesis. 
 $e studies mentioned above include di!erent 
parameters and testing conditions, yet all reached 
the same conclusion that alpha-lactalbumin 
consumption yields the highest Trp:LNAA ratio, 
thus increasing sleep quality through melatonin 
production.  
 
5. Changes in Sleep Quality "rough Chrono-
nutrition  
 Because research suggests that the e!ectiveness 
of dietary components can be associated with 
intake time, then milk consumed within 2 hours 
of a DSPD patient’s desired sleep time could yield 
a net improvement in sleep quality and morning 
functionality on the following day because of the 
patient’s susceptibility to changes in bodily hormones.     
Richard et al. (2009) brie'y introduced the idea 
that tryptophan availability and serotonin synthesis 
e%ciency can be impacted through the timing of 
consumption. $e macromolecules in foods can 
break down and enter di!erent synthesis pathways 
depending on their homeostatic necessity at that 
speci"c time. Berendsen et al. (2020) researched the 
phenomenon of timed dietary intake, or chrono-
nutrition, and diet quality in adolescents with DSPD 
to measure the conjoined e!ect of diet and timed 
consumption to create a circadian balance. $ey 



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Aisthesis      Volume 13,  202262

experimented on relatively healthy DSPD patients 
aged 13 to 20 years due to a 7-16% prevalence of 
DSPD within the age range. Individuals who have 
decreased sleep duration tend to have lower leptin 
levels and increased ghrelin levels, meaning that 
there is decreased satiation and increased hunger; 
researchers noted that this was associated with 
adverse health e!ects and a high BMI. Zeng et al. 
(2014) added that sleep restrictions can overstimulate 
the hypothalamus, the brain region that is sensitive 
to food stimuli, to decrease leptin circulation and 
increase ghrelin concentrations. Zellner et al. (2006) 
asserted that increased cortisol and ghrelin levels 
cause individuals to stray from healthy, low-fat foods 
to high-fat foods; the fat content tends to make 
individuals feel emotionally secure. In application to 
DSPD patients with abnormal circadian schedules 
and decreased sleep durations, unhealthy foods tend 
to stimulate their hunger hormones, making them 
susceptible to having a high BMI. In DSPD patients 
with high cortisol levels, their hypothalamus will 
increase ghrelin secretion to address poor sleep 
health with increased food intake. Increasing cortisol 
levels is a sympathetic response that causes a domino 
e!ect on decreasing digestive powers and increasing 
ghrelin. Since the digestive juices are not functioning 
at potential due to high cortisol, the food intake will 
have a high chance of being stored directly as fat. All 
these researchers similarly concluded that disruptive 
sleep schedules can increase ghrelin levels and 
contribute to adverse health e!ects. 
 Regarding the previously mentioned idea of 
chrono-nutrition, Markus et al. (2005) found that 
the consumption of a-lac in the evening can be timed 
properly to peak at speci"c times and induce sleep. 
$ey determined that the Trp:LNAA levels reached 
an apex at 3 hours a&er the initial consumption of 
a-lac, and the e!ects settled down to a base rate 5 
hours a&er intake; within that interval, the DSPD 
patients reported better sleep quality due to a deeper, 
REM sleep stage, and they had greater morning 
alertness on the following day. As stated before, 
supplements can have excess side e!ects if they are 
not taken at an exact time, but the same cannot 
necessarily be stated with milk. Milk has quantities of 
a-lac and tryptophan that are high in comparison to 
other foods, but not enough to create nausea or other 
side e!ects when taken at the wrong time. Yet, DSPD 
patients should aim to drink the milk approximately 
2 hours before they plan on going to sleep because 

their melatonin will begin to surge during that 
time, allowing them to have a shorter sleep latency 
and maximum sleep e%ciency (Markus, 2005). It is 
indeterminate whether milk is substantial enough to 
phase shi& the circadian rhythm to a desired time, 
but it can allow the body to adjust accordingly.  
 Some individuals cannot shi& their schedule to a 
desired time because of life constraints; therefore, this 
method can primarily be used to improve the sleep 
that they receive rather than advance their circadian 
schedules to an alternative time. Chrono-nutritional 
di!erences in young adults with DSPD can alter how 
the molecules from foods can be synthesized. In the 
evening, the nutrients and macromolecules obtained 
from milk can be utilized towards synthesizing 
melatonin as a preparation for sleep, working in 
conjunction with the nightly activated pineal gland.  
 
6. Subjective Testing and Experimental Proposal 
for the MILC Treatment  
 Because there is subjectivity in testing for 
sleep quality, multiple quanti"able tests, individual 
ratings, and sleep EEGs are required to measure the 
sleep activity and depth of sleep to create an overall 
interpretation of sleep quality in DSPD patients.  
 Patients with DSPD have speci"c de"nitions 
of a healthy, restorative sleep because of biological 
predispositions, but most generally have normal-
high BMIs because of their susceptibility to unhealthy 
lifestyles. To quantify a patient’s health and diet 
quality, Berendsen et al. (2020) referred to the Dutch 
Healthy Diet (DHD) index that places exercise, 
food quality, and drinks on a scale. Information 
on chrono-nutrition and alpha-lactalbumin are 
scarce, but researchers are expanding on the idea 
that chrono-nutrition and intake of a-lac can 
conjunctively alter an individual’s sleep quality. To 
verify this connection between tryptophan, sleep, 
and chrono-nutrition, Markus et al. (2005) tested 14 
subjects who were considered “good sleepers” and 14 
subjects who were considered “poor sleepers.” $e 
morning a&er providing the subjects with evening 
a-lac, Markus et al. (2005) measured the e!ectiveness 
of the protein on sleep quality by subjectively asking 
the participants to rate their alertness levels on 
the Stanford Sleepiness Scale. Another alertness 
quanti"cation method was through physical 
and mental challenges in which the participants 
completed continuous performance tasks (CPT) 



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Aisthesis      Volume 13,  2022

to determine their agility, accuracy, and speed. As 
a last form of data quanti"cation, the researchers 
performed EEGs and event-related potential (ERP) 
tests to analyze the eye-movement signals and deep 
sleep stages. All these methods of measurements 
accurately showed net improvement in the poor 
sleepers who consumed a-lac, and the results from 
each test correlated with this result, supporting the 
accuracy of these alertness tests. $ese alertness and 
sleep tests were performed to acquire an average, 
quanti"able measurement of sleep quality, and in 
future follow-up studies, the same tests should be 
performed to conduct baseline comparisons.
 A follow up study needs to be conducted to 
test the e%cacy of the MILC treatment, consisting 
of DSPD patients within the ages of 18-30. Subjects 
should be considered high-stressed based on the 
Perceived Stress Scale (PSS) in which individuals’ 
stress levels are categorized and assessed using 
subjective life situations. Researchers should 
determine the length of the study depending on 
parameters, but control and experimental groups 
should have the same diet quality based on the Dutch 
Healthy Diet (DHD) index. $e experimental group 
should have a set milk intake time in the evening, 
preferably 2 hours before the subjects go to sleep. $e 
amount of light exposure for the test subjects should 
also be kept similar because external exogenous 
factors can negate the e!ects of milk intake. To 
obtain results, the Trp:LNAA ratio should be 
measured in individuals before, during, and a&er the 
experimental manipulation of chrono-nutrition and 
milk consumption. As for melatonin concentrations, 
the DLMO pro"les should be assessed through the 
collection of saliva to evaluate the e!ectiveness of 
the endogenous circadian rhythm and the pineal 
gland melatonin releases. A sleep EEG can be used 
to determine the sleep stages and rhythms that 
an individual experiences over the course of the 
night. To acquire a combined, quanti"able result, 
standardized sleep scales and deep sleep brain 
waves should be utilized to determine sleep quality 
in patients with DSPD. Alterations to the MILC 
treatment, such as adjusting the temperature of milk, 
can possibly a!ect its sleep inductive qualities and 
a%nity to the BBB, but further research is needed on 
the subject.  
  $e MILC treatment suggests that a potential 
solution for DSPD patients’ sleep quality is the 
ingestion of one cup of whole cow’s milk to raise 

melatonin levels at night and induce deeper 
sleep. Considering chrono-nutrition, high-stress 
individuals who consistently time their high-
tryptophan diets can yield the greatest increase in 
their Trp:LNAA ratio, enabling melatonin synthesis 
to e!ectively enhance agility and morning alertness. 

7. Discussion 
 Individuals who maintain a relatively healthy 
lifestyle and diet, even when struggling with an 
unbalanced sleep schedule, can counteract negative 
symptoms through small alterations in their lifestyles. 
Consider DSPD patients who are high-stressed and 
unhealthy in terms of both sleep and diet; these 
adversities inhibit internal regulation of hormonal 
concentrations and can pave a path for serious 
illnesses. At the core of treating their disorder, these 
individuals need to obtain a balance of the sleep 
hormone, melatonin, to rise and fall at set times. To 
achieve this goal, the MILC treatment acts upon the 
concept of chrono-nutrition, or timed consumption, 
to raise the chances of molecular components entering 
a speci"c synthesizing pathway. For this theoretical 
treatment, DSPD patients will consistently consume 
1 cup of whole cow’s milk at a predetermined time 
based on individual needs. Over time, the individuals 
should sense an improvement in morning alertness 
and enhanced sleep quality, averting negative health 
e!ects. Synthesizing melatonin and combating an 
altered circadian schedule through milk can be a 
non-supplemental method to naturally reestablish 
a healthy sleep cycle. Although consumption of 
milk once will not establish results immediately, 
a consistent sleep, diet, and exercise schedule is 
crucial in e%ciently regulating the body. Body types 
can contribute to an individual’s response to the 
MILC treatment, but further research is needed to 
determine and adjust speci"c quantities of milk and 
timing of consumption. $is potential treatment is 
meant to be an alternative method to supplements, 
and it can only work if an individual does not 
hinder the process through unnecessary exposure to 
delaying exogenous factors. A DSPD patient needs to 
be receptive towards alternative treatment methods 
that target speci"c symptoms, and the only way to 
"gure out the best needs for a speci"c individual is 
through trial and error.  
 
 

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