Improving sleep quality, psychosocial functioning, and cancer related fatigue with light therapy (SPARKLE-study).

Cancer related fatigue (CRF) is one of the most prevalent and distressing
long-term complaints reported by (non-)Hodgkin survivors. So far, there is no
standard treatment. Some non-pharmacological interventions have shown large
effects but show limitations as well, e.g. they are labour intensive. A novel
and promising treatment for CRF is exposure to bright white light (BWL)
therapy. This low-cost intervention is easy to deliver and has a low burden for
professionals as well as for patients.

(1) To examine whether the exposure to BWL yields clinically significant
reductions in CRF compared to exposure to dim white light in (non-)Hodgkin
survivors.
(2) To examine the effect of exposure to BWL compared to DWL on sleep quality
and psychological variables (depression, anxiety, cognitive complaints, and
quality of life).
(3) To investigate whether exposure to BWL, compared to DWL, affects biological
circadian rhythms (reflected in variability in cortisol and melatonin levels),
circadian physical activity rhythms (actigraph), and concentrations of vitamin
D and inflammation markers (hsIL-6, hsCRP, sTNF-RII, and IL-1RA).
(4) To explore whether the effects of exposure to BWL, compared to DWL, on CRF
are predicted by the effect of BWL on sleep quality, psychological variables,
biological and physical activity circadian rhythms, and biological factors
associated with fatigue.
(5) To explore the association between changes in the production of cortisol
and melatonin with cancer related fatigue.
(6) To investigate whether the efficacy of light therapy is associated with
specific genotypes.

This explanatory clinical trial will use a double blind randomized controlled
trial design with one intervention group exposed to BWL and a control group
exposed to DWL. Upon completion of the study, the patients assigned to the
control group will be given the opportunity to receive the intervention.

All participants will be asked to complete a battery of questionnaires prior to
light therapy (T0), immediately post-intervention (T1), at 3 months (T2) and at
9 months (T3) follow-up. Furthermore, participants will be asked to wear an
actigraph to determine sleep-wake cycles for 10 days at all measurement points.
This will be combined with the completion of a sleep diary. Moreover, blood and
saliva samples will be collected at T0 and T1 for those participants that
consent to provide these materials.

The light intervention includes exposure to bright white light (10.000 lux at a
distance of 45 cm) for 30 minutes within the first half hour after awakening
during 3 weeks and 4 days. This can be done while engaged in other activities,
for example reading the newspaper or eating breakfast). Participants in the
control condition receive the same instructions but are exposed to dim white
light (10-20 lux at a distance of 45 cm).

Participation in this study includes completion of a light intervention for
three weeks and four days (30 min each day) and 2 visits (1h) to the treating
hospital pre- and post-intervention. The visits aim to complete three cognitive
tasks (15 min), provide instructions and equipment and to collect blood samples
(two tubes per visit). Additionally, 5 (or 10) saliva samples will be collected
by the participant at home pre- and post-intervention. Moreover, participants
complete questionnaires (30 min, 4 times) and wear an accelerometer (10d, 4
times) to objectively measure sleep quality and activity. Risks of the light
intervention are limited, although there are few known reports of agitation,
headache and nausea during the first days of light exposure. Benefits are the
use of an easy to administer treatment for one of the most distressing symptoms
frequently reported by (non-) Hodgkin survivors.