Why Won’t My Patient Sleep!
The Intensive Care patient will often lie awake at night, eyes wide open, clearly with no intention of sleeping. So why won’t the intensive care patient sleep? Perhaps we need to understand what happens during normal sleep and take it from there…..
Stages of sleep
Sleep is divided into non-rapid eye movement and rapid eye movement phases. The non-rapid eye movement stage is further divided into three different stages. The third of these, stage N3, is significant for its role in restorative processes.
Rapid eye movement sleep occupies 20% to 25% of the total sleep period. The brain is highly active in this period is associated with dreaming.
The circadian rhythms which drive the sleep wake cycle is regulated by adenosine and melatonin. One helps us sleep the other helps us keep awake.
What happens during sleep?
During sleep there is a loss of compensatory responses, such as shivering and sweating. The body temperature reaches its lowest point during the latter part of sleep and then rises prior to awakening.
Voluntary control of respiration is lost during sleep. Moving from being awake to the early phases of sleep is marked by a reduction in minute volume. Due to relaxation of upper respiratory muscles, increased airway resistance, and diminished central respiratory drive hypoventilation can occur which will increase arterial PCO2 levels.
During non-rapid eye movement sleep increased parasympathetic tone causes a decreased blood pressure, heart rate and systemic vascular resistance.
There is more variability during rapid eye movement sleep. There may be bursts of vagal activity and along with decreased sympathetic tone there may be bradyarrhythmias and sinus pauses.
Growth hormone and prolactin peak during sleep. Cortisol levels are also at their lowest level after sleep onset. Thyroid stimulating hormone is inhibited during sleep and will increase with sleep deprivation.
Sleep in ICU
Patients in intensive care commonly report poor sleep quality and surveys of survivors have shown that sleep deprivation ranks among the top three major sources of anxiety and stress during their stay in intensive care.
50% of their sleep will occur during daytime hours, and the average approximately 41 sleep periods per 24 hours each one lasting approximately 15 minutes. They commonly go through the first two stages of sleep without then moving onto the latter stage and rapid eye movement sleep. In other words they have broken light sleep without the restorative stages needed.
Causes of sleep disruption.
Noise– staff conversations, alarms, telephones and televisions are commonly quoted as being the causes of the noise within the intensive care unit. The recommendation is for maximum hospital noise levels of 45 dB during the day and 35 dB at night. Commonly however both daytime and night time noise levels routinely exceed 80 dB.
Patient care activities– patients in intensive care may experience 40 to 60 interruptions each night due to activities such as patient assessments, vital signs and is, equipment adjustment and medication administration to name a few.
Light– intensive care survivors have reported that light is less disruptive than noise and patient care activities. However it is known that nocturnal melatonin secretion in intensive care patients can be suppressed, causing further difficulties in sleeping.
Mechanical ventilation– the patient that is ventilated as compared to the patient that isn’t is more likely to suffer from sleep deprivation. This is due to factors such as increased ventilatory effort, abnormal gas exchange, and patient ventilator dysynchrony. Other factors may include endotracheal tube discomfort, ventilator alarms, suctioning, positioning, and frequent assessments.
Medications-some commonly used medications in intensive care can have profound effects on sleep quantity and quality. The sedation we use with many of the patients in intensive care is also disruptive to sleep. For example opiates such as fentanyl and morphine inhibit rapid eye movement sleep, profoundly suppress the latter stages of non-rapid eye movement sleep and can provoke awakening at night. Benzodiazepines and opiates are also associated with delirium in critically ill patients.
Propofol suppresses the latter stages of non rapid eye movement sleep whereas dexmedetomidine has been shown to enhance this stage of sleep in a rat model.
Psychological consequences of sleep deprivation in critically ill patients.
Delirium– delirium is associated with patient mortality, increase cost and length of stay and long-term cognitive impairment. It is possibly difficult to say whether sleep deprivation directly contributes to delirium but circadian rhythm disturbance, sedating medications and opiates contribute to both delirium and sleep disruption.
Psychiatric disturbances– survivors of critical illness often experience frightening flashbacks, nightmares, anxiety, and mood disturbances related to their intensive care stay.
Post-traumatic stress disorder has been shown in 10% to 39% of intensive care unit survivors during their first year after the intensive care unit stay. Post-traumatic stress disorder symptoms have been present in up to 45% of those discharged and is still present in 24% at 8 years after intensive care unit discharge.
Depression among survivors is also very common and has been shown to be present in 28% of patients within the first year of intensive care unit discharge. In those that suffered from ARDS the prevalence of depression is a size 46% at one year and 23% at two years after discharge.
Many studies have demonstrated depressive symptoms and increase levels of fatigue anxiety and stress in healthy participants undergoing total or partial sleep restriction. Sleep disruptions in the critically ill patient may be contributing to post intensive care unit psychiatric disorders. This is possibly not that well understood at the moment.
Cognitive dysfunction-impairment of memory, attention, concentration, language, mental processing speed, visuospatial abilities and executive function have all been shown to have been affected following critical illness. Some of the causes are thought to include delirium and sedating medications.
Due to neuro cognitive dysfunction many intensive care unit survivors experience challenges with daily functioning, social isolation and difficulties returning to work.
Quality of life-health-related quality-of-life concerns one’s perception of overall well-being and incorporates measures of physical, mental, emotional, and social functioning. Critical illness is associated with long-term impairments in quality of life for many years after intensive care unit discharge chronically reduce sleep also leads to reductions in quality of life.