Neuroscience & Medicine, 2013, 4, 150-154
http://dx.doi.org/10.4236/nm.2013.43024 Published Online September 2013 (http://www.scirp.org/journal/nm)
Stabilization of Circadian Rhythm, Its Augmentation by
Bright Light Treatment and Its Importance for ADHD and
Depression of Adole scents
Helmut Niederhofer
Department of Child and Adolescent Psychiatry and Psychotherapy, Saechsisches Krankenhaus für Psychiatrie und Neurologie
Rodewisch Bahnhofstrasse, Rodewisch, Germany.
Received March 11th, 2013; revised April 14th, 2013; accepted May 8th, 2013
Copyright © 2013 Helmut Niederhofer. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Objective: ADHD is ch aracterized by the progressive development of, imp ulsiveness, attentional difficulties and some-
times also excessive hyperactivity. Main biological reason is a quantitative reduction of the neurotransmitter dopamine
in the forebrain. A lack of dopamine is also typical for depressive disorders. Methods: Bright light therapy is proven to
be effective in treating depression. Purpose of our study is to verify the therapeutic effectiveness of Bright light therapy in
subjects affected by ADHD. Results: Results show a significant improvement which lasts for at least 4 weeks, which is
superposed by regulation of the circadian rhythm. Initial decrease of especially mornin g saliva melatonin levels, due to
regular sleep under in-patient conditions, is followed by symptom improvement and a raising evening melatonin level,
due to activation during the day. This level decreases as soon as activation is ceased. Conclusion: Bright light therapy
seems to be effective as add-on therapy for ADHD, but in fact, stabilization of the circadian rhythm is the most impor-
tant therapeutic in tervention, either for ADHD or for depres si on , as demonstrated in anot her study .
Keywords: ADHD; Circadian Rhythm; Bright Light Therapy
1. Introduction
ADHD is characterized by the progressive development,
impulsiveness, attentional difficulties, which influences
also interpersonal relationships, and sometimes also of
excessive hyperactivity. Today, research has been of low
specificity and used diagnostic criterions, absent from
specific biological markers, and has been characterized
by the scarce answer to the conventional pharmacologi-
cal treatments. Recently, some researchers have under-
lined the presence of a direct correlation of the severity
of symptomatology and psychometric markers, such as a
quantitative reduction of dopamine, especially in the
right frontal lobe. Such parameters seem also to be modi-
fied by the administration, e.g. Methylphenidate [1]. A
lack of dopamine is also typical for depressive disorders.
Additional biological therapies, which elevate cerebral
dopamine levels, like repetitiv e transcranial magnetic sti-
mulation (rTMS) have been proven to be effective treat-
ing patients suffering from depression [2] and ADHD [3].
Bright light therapy also elevates cerebral dopamine lev-
els and is proven to be effective treating depression [4].
One open trial, including adults suffering from ADHD [5]
suggests that it might be also effective in wintertime and
for ADHD, at least as additional therapy. Purpose of this
placebo-controlled observation in 28 adolescents is to
verify the therapeutic effectiveness of Bright l ig ht th era py
in 28 adolescents affected by ADHD.
2. Methods
28 volunteers, aged 14 - 17 years, IQ 96 - 105, were re-
cruitred in the Dep. of Child and Adolescent Psychiatry
of the Hospital of Rodewisch from March 2011 to June
2012. Patients suffered from ADHD for more than two
years. Informed consent was obtained from each partici-
pant prior to the start of the study, in accordance with the
guidelines set forth by the Declaration of Helsinki. Pa-
tients were encouraged to continue ongoing treatment
(both received 40 mg Methylphenidate daily and Psy-
chotherapy) during the study, with the assumption that
psychotherapy and medication effects over an interval of
4 weeks were likely to be small, since there was no
change of medication/dosage and psychotherapy (2 ses-

Stabilization of Circadian Rhythm, Its Augmentation by Bright Light Treatment
and Its Importance for ADHD and Depression of Adolescents 151
sions/week) since one month before the 4 week study
period.
ADHD symptoms were assessed weekly by the Con-
ner scales [6]. This test has an excellent variation sensi-
tivity and an 81% sensitivity and 61% specificity for
ADHD. It consists of 20 items, 10 of which describe in-
attention and 10 describe hyperactivity. The items are to
be rated on a scale from 0 = never existing to 3 = always
existing. Each of the two subscales has a cut-off of 14, i.e.
that scores of >14 are typical for ADHD.
Step 1 (Baseline): 28 Volunteers were admitted and
began with the initial baseline week of the study. The
purpose of the baseline week of the study was to be able
to differentiate change s of the Conner score between out-
and in-patient treatment and to that of placebo and BLT
treatment. Conner scores were measured at the day of
admission and one week after admission (Prae-trial).
Step 2 (Verum): In the second week of the study, the
28 patients were asked to sit alone in front of the bright
light box (2500 lux) from 09:00 to 10:00 a.m. In this time,
patients played or listened to a story. Conner scores were
measured after the second week.
Step 3 (Placebo): In the third week of the study, the 28
volunteers were asked to sit alone in front of the placebo
light box for (50 lux) 60 minutes in the morning, from
09:00 to 10:00 a.m, In this time, patients played or lis-
tened to a story. This aspect of the design followed the
general principle of clinical trial design that better con-
trasts between active and placebo. As reviewed by East-
man [7], the issue of placebo responses has been a seri-
ous problem in clinical bright light studies, though the
placebo problem has been negligible in studies of the
physiologic effects of light. Conner scores were meas-
ured after the third week.
Step 4 (Post): In the fourth week of the study, the 28
patients received neither placebo nor BLT. The purpose
of this week of the study was again to be able to differ-
entiate changes of the Conner score related to ADHD to
that of placebo and BLT treatment. Conner scores were
measured after the fourth week.
Saliva samples were collected one week before (Base-
line) and one day be fore placebo treatment (Prae), on the
day between verum and placebo treatment (Verum), on
the day after placebo treatment (Placebo) and one week
after placebo treatment (Post), at each time at 08:00 a.m.
and 08:00 p.m., and assayed for melatonin to characterize
the circadian phase of the subject’s melatonin rhythms
(ELISA, Immuno Biological Laqboratories, Hamburg,
Germany). Saliva samples were used because of the con-
venience for the patients.
The subjects completed a weekly Assess ment for Treat-
ment Emergent Events (SAFTEE) symptom scale. Four
weeks of treatment were carried out with weekly symp-
tom assessments. The investigators visited su bjects weekly
to assure their safety and their compliance with the study,
and to administer and collect rating forms.
3. Results
Subjects’ moods and salivary melatonin levels improved
under both treatments (Table 1). With respect to inatten-
tion, Conner scores were stable in the pre-treatment pe-
riod (Score 16.3, cut-off 14), improved during treatment
with bright light therapy to the score of 12.7. In the pla-
cebo and post-treatment period, the score rose again up
to 15.8 (Figure 1).
Regarding hyperactivity, Conner scores dropped in the
pre-treatment period from 17.4 to 16, improved during
treatment with bright light therapy to the score of 13.6. In
the placebo and post-treatment period, the score rose
again up to 16.9 (Figure 1).
Salivary melatonin, measured in the morning, showed
a remarkable decrease from the pre-treatment period (13
pg/ml-range < 10 pg/ml) to the BLT, placebo-, and the
post-treatment period (4pg/ml). Salivary melatonin,
measured in the evening, also decreased slightly in the
pre-treatment period from 8 pg/ml to 5 pg/ml (range > 10
pg/ml), and increased after placebo to again 8pg/ml, after
BLT even to 9 pg/ml, and to 12 pg/ml in the post-treat-
ment week (Figure 2).
Significant differences of Conner scores and melatonin
levels are depicted in Table 1.
Participants experienced no suicide attempts. There
were no incidents of mania or hypomania during the light
treatment.
The weekly SAFTEE physical symptom inventory
(range: severe-moderate-mild-minimal-not existing) was
examined for adverse reactions. The symptom Headache
improved with bright light in one patient from mild to
minimal, and with dim light, nausea and vomiting im-
proved in the other patient also from mild to minimal.
This improvement lasted until th e end of the study. With
respec t to the other symptoms, patient did not repo rt any
change, i.e. they were always scored as “minimal” or
“not existing”, without any changes in the four weeks.
4. Discussion
BLT led to a significant reduction of the Con ner Inatten-
tion score and also showed an improvement in the Con-
ner Hyperacivity Score. In addition, the social structure
and regularized sleep might be beneficial. Interestingly,
there was a more significant decrease in the Hyperactiv-
ity than in the Inattention Score, which suggested that
BLT was more effective in case of Hyperactivity than of
Inattention. This corresponds to recent findings which
suggest biological therapies (such as sleep regulation and

Stabilization of Circadian Rhythm, Its Augmentation by Bright Light Treatment
and Its Importance for ADHD and Depression of Adolescents
152
Figure 1. Changes of ADHD Scores before, during and after Bright light Therapy.
Figure 2. Changes of Morning and Evening Melatonin Saliva levels before, during and after Bright light Therapy.
BLT in our trial) to be more effective for Hyperactivity
than for Inattention.
It was also evident that both scores did not change sig-
nificantly in the pre-treatment period, i.e. in the first
week after admission. The morning melatonin level de-
creased significantly in the first week after admission, the
evening melatonin level in a non-signif icant way. During
BLT, the morning melatonin level remained stable within

Stabilization of Circadian Rhythm, Its Augmentation by Bright Light Treatment
and Its Importance for ADHD and Depression of Adolescents 153
Table 1. Differences of ADHD Scores and Melatonin saliva levels before, during and after Bright light Therapy.
Wilks Lambda 1 Factor Analyasis of Variance, corrected by Bonferoni
Differences between
BLT and
Differences between
Placebo light and Differences Baseline to…
Baseline Prae Placebo Post BaselinePrae Post Prae Post Prae to Post
F p p p p p p p p p p p
Attention 3.96 0.011 0.013 0.005 0.001 0.007 n.s. n.s. n.s. n.s. n.s. n.s.
Hyperactivity 4.11 0.025 0.006 0.003 0.001 0.005 n.s. n.s. n.s. n.s. n.s. n.s.
Melatonin
morning 5.62 0.012 0.006 0.004 0.004 0.002 n.s. n.s. n.s. n.s. n.s. n.s.
Melatonin
evening 3.34 0.039 0.017 0.014 n.s. 0.008 n.s. 0.012 0.003 n.s. n.s. 0.002
the normal range, whereas the evening melatonin level
rose step by step, also under placebo and in the post-
treatment period, up to the normal range. These facts
suggest, that the regulated circadian rhythm under in-
patient condition seems to be more important than BLT.
In the first seven days after admission patients, regular
sleep is compensated by excitement which leads to a de-
crease of both melatonin morning and also for evening
levels. Morning melatonin levels remain then stable (in-
dependently of BLT, due to continued regular sleep con-
ditions), whereas evening melatonin levels raise step by
step, also independently of BLT, which might be due to
physical activation during the day. Altogether, BLT im-
proves clinical ADHD symptoms, Hyperactivity more
than Inattention, but with respect to both morning and
evening melatonin levels, a regular circadian rhythm
seems to be more important than BLT. Furthermore, a
normalization of the morning melatonin level also seems
to improve ADHD symptoms, followed by the normali-
zation of the evening melatonin level. The fact that espe-
cially the Hyperactivity score does not reach the pre-
treatment value suggests that physical activation during
the day under in-patient conditions itself improves Hy-
peractivity. BLT has only an additional effect. Anyway,
our data suggest that the circadian rhythm, objectivated
by salivary melatonin levels, is also deranged in case of
ADHD. It can be concluded, that the normalization of the
morning melatonin level induces improvement of clinical
symptoms, which itself induces normalization of the
evening melatonin level. According to our results, there
seems to be a causal association between melatonin lev-
els and clinical symptoms, which may be caused by im-
portant confunding variables (sleep regulation, physical
activation, etc.) affecting the melatonin levels and clini-
cal symptoms at least as much as BLT itself. It can be
concluded that regular sleep (objectivated by morning
melatonin level) induces improvement of clinical symp-
toms which enables the patient to be more active during
the day (objectivated by evening melatonin level). Mela-
tonin levels must decrease rapidly i.e. melatonin storages
must be depleted rapidly first. Then, clinical symptoms
will improve and the circadian clock (suprachiasmatic
nucleus) will work properly and refill the melatonin
storage at night.
Sleep deprivation augments this procedure: first, de-
pleting the melatonin storage and then refilling it by
means of a properly working circadian clock. One night
without sleep fills the melatonin storage in the morning
and further until the following day’s ev ening (the patient
does not feel better that day, only more tired) and it’s then
depleted rapidly the next night, when the patient sleeps,
which improves clinical symptoms in the following day
and enables the patient to be more active that day and,
based on this, reorganizes the circadian clock, filling the
melatonin storage correctly during the day. The reason,
why sleep deprivation must not last for more than one
night is that the melatonin stor age is completed after that
time and refilled in the following night. It is an adjunc-
tive strategy to support rapid depletion of the melatonin
storage indirectly by filling it previously—with the aim
to reorganize the circadian clock which fills the melato-
nin storage agai n.
Altogether, it seems to be more important to deplete
the melatonin storage rapidly first than to fill it, e.g. ad-
ministering melatonergic drugs such as melatonin or ago-
melatine. These drugs should only be given if regular
sleep with an immediate effect and physical activation
during the day with a delayed effect as first steps did not
show a sufficient improvement for some weeks.
Interestingly, we saw similar effects, investigating
BLT for adolescents suffering from depression: initially
morning melatonin levels decreased (due to regular sleep
under in-patient conditions and evening melatonin levels
remained stable due to physical activation during the
day), followed by an improvement of clinical symptoms
and a normalization of evening melatonin levels (due to
physical activation), amplified by BLT [8]. Ceasing the
physical activation led to a new decrease of evening me-

Stabilization of Circadian Rhythm, Its Augmentation by Bright Light Treatment
and Its Importance for ADHD and Depression of Adolescents
154
latonin levels. It can be assumed that a new dysregulation
of sleep conditions might also lead to a new gain of
morning melatonin levels.
Altogether, regular sleep (morning melatonin levels
react immediately) and physical activation during the day
(evening melatonin levels react with a delay) seem to be
more important than BLT itself, which amplifies this
effect. This effect can be seen in patients suffering either
from depression or from ADHD.
Apart from an advantage on one scale (Head) of the
SAFTEE side effects inventory, bright light treatment
was superior to dim placebo light. The beneficial effects
found in the study might be attributed to several factors
that were common to the treatment and control groups.
The “placebo” effect, chiefly positive expectations, and
positive staff contacts may have contributed to positive
responses. An hour a day engaging in a treatment, which is
thought to be helpful, may have induced a reduction in
ADHD symptoms. A longer period may be needed for
this population with ADHD symptoms.
Rhythms of melatonin, sleep, and activity all peak la-
ter in ADHD patients as compared to healthy controls.
However, since increased light exposure is generally as-
sociated with more advanced rhythms (as was observed
comparing the bright light and placebo period in this
study), the results are consistent with the possibility that
these patients are subsensitive to circadian effects of
light.
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