Previous research has shown that sleep quality in hemodialysis patients is disturbed. One of the possible explanations is an insufficient or disturbed melatonin rhythm. Melatonin rhythm is regulated by exposure to light. In this feasibility study, the investigators examine the effects of light therapy during dialysis on sleep, melatonin rhythm and mood.

Inclusion Criteria:

• informed consent
• men/women aged 18-85 years
• knowledge of the dutch language
• hemodialysis patient
• subjective sleep problems (Epworth sleepiness score >9)

Exclusion Criteria:

• known major illness, which interferes with patient's participation
• use of melatonin/hypnotics
• use of photosensitizing medication
• jet lag or travel > 1 time zone