Sleep-wake dysregulation is a disturbance in the roughly 24-hour cycle of the circadian rhythm. Well known disorders presenting a sleep-wake dysregulation are seasonal affective disorder, jet lag and shift work. These people experience a serious mood change when the seasons change. When the day-night rhythm is desynchronized, they have sleep disturbances, little energy, and often feel depressed. An established intervention to treat this disorder is bright light therapy. Light therapy is used for affective disorders for shift workers, jet lag symptomatology and for advancing or delaying desynchronized rhythms.Two proxy measures for sleep-wake dysregulation are sleep quality and daytime sleepiness. It is known from cross sectional studies that renal transplant (RTx) recipients have a prevalence between 30% to 62% of poor sleep quality measured by self report; a prevalence of impaired daytime functioning of 34% 12 and a prevalence of depressive symptomatology of 20% to 22%. Sleep-wake dysregulation in other chronically ill population are a risk factor for morbidity and mortality.

RTx nurses in the follow-up care are in the frontline for recipient's symptoms respectively problems. The psychosocial variables that should be addressed, having an association with morbidity and mortality are sleep, daytime functioning, adherence to immunosuppressive medication, exercise, smoking and depressive symptomatology.

In the following research project we will address the following gaps: the fact that nature of sleep disturbances in RTx recipients has never been assessed, that there is no prevalence available on sleep-wake dysregulation and that there is no data on bright light therapy intervention in RTx recipients.

Hypothesis: Renal transplant recipients having a sleep wake disregulation will have an improved sleep quality and less daytime sleepiness after 21 days of light therapy.

This research project has three phases:

The first phase is a cross sectional survey including all patients transplanted in Basel, Bern and in Zurich speaking German and transplanted at least 6 months ago. Renal transplant recipients having poor sleep quality and / or daytime sleepiness as result of this first phase will be asked to participate in phase two. Phase two is an sleep assessment, resulting in a presumed sleep diagnosis.

Renal transplant recipients having a sleep wake dysregulation, assessed in phase two, will be asked to participate in phase three. Phase three is a pilot randomized controlled trial to compare the sustained impact of bright light therapy on sleep-wake regulation.

Inclusion Criteria:

• For phase 1: all renal transplant recipients transplanted at the University Hospital Basel, Bern and Zurich, speaking German and having an actual address on the follow-up list of the ambulatory center list.
• Renal transplant recipients who have poor Sleep quality and /or daytime sleepiness (phase 1: Cross sectional survey study) and had a Sleep assessment (phase 2: Cross sectional diagnostic interview study)
• Renal transplant recipients who participated in Phase 1 and 2 that were diagnosed with sleep wake dysregulation
• Renal transplant recipients with signed written informed consent.

Exclusion Criteria:

• RTx recipients, who participated in phase 2, will be excluded in the study if

  • they were diagnosed with sleep disorders as parasomnia, breathing disorders or movement disorders.
  • they were diagnosed with alcohol or substance abuse
  • they are blind or suffer from a severe vision impairment (cataract), which possibly limits the effect of the light intervention and patients taking photosensitive medications

2 months

2 months beginning with the start of the study.

The study was very long and burdensome for the participants, a full powered study should be shorter.