Sleep and rest are key elements in postoperative rehabilitation and recovery. There are complex relations between major surgery, sleep disturbance and complications. Major surgery leeds to severe postoperative sleep disturbances, initially reducing REM sleep time and disturbing the remaining sleep stages. Major surgery is again a risk factor for postoperative delirium and other cognitive impairment. The underlying mechanisms includes pain, opioid medication, sleep disturbances and neuroinflammation, along with external factors as noise during hospitalisation. The physiologic stress from sleep disturbances and sleep deprivation is associated with blood-brain barrier impairment, inflammation, decreased restitution, altered nociceptive function. Likewise, undiagnosed and untreated sleep apnea is a risk for postoperative complications and is itself affected by anesthesia and some analgesics (i.a. opioids).

Fast-track surgery development has led to restitution period shortening, optimized pain management reducing opioid use, postoperative inflammatory stress response reduction and less delirium. Evolution of hip and knee arthroplasty(THA/TKA), organisation, optimized pain management and pharmacologic modification of inflammatory response by high dose steroid has permitted to perform these surgeries in an outpatient setting.

Previous studies of fast-track THA/TKA using multimodal opioid-sparring analgesia, however neither using high dose steroids nor in an out patient setting, have demonstrated REM sleep period reduction from a normal range of 18% preoperatively to 1% postoperatively. However, changes in sleep architecture after THA/TKA in at setting attempting to minimise abnormal sleep by means of ambulatory surgery added to perioperative reduction of inflammatory response to surgery, pain and opioid use by high dose steroid, haven't been studied.

The purpose of this study is to investigate how much an optimized ambulatory THA/TKA , reducing pain and inflammatory response to surgery and opioid use by high doses steroid can conserve the preoperative sleep architecture.

Inclusion Criteria:

• ASA classification I or II
• Scheduled hospital discharge same day after surgery
• Adult person following the patient 24 hours at the patients habitation
• Informed consent and signature.
• Patient speaks and understands Danish

Exclusion Criteria:

• Hospital discharge later than same day after surgery
• No consent form patient
• Alcohol or drug abuse
• Anxiolytic og antipsychotic treatment
• Preoperative opioid treatment
• Soporific treatment

16 adult attending scheduled hip or knee arthroplasty in an ambulatory fast-track setting with spinal anesthesia corresponding to the above mentioned inclusion criteria.