Table 1.
Sleep Disturbances in Critically Ill Patients
| Patient-related
factors | |
| Preexisting sleep
disorders | |
| Pain | |
| Anxiety | |
| ICU-related factors | |
| Noise | |
| Light | |
| Patient care
activities | |
| PSG findings in critically ill
patients | |
| TST | Unchanged/decreased |
| TST occurring during daytime hours | 50% |
| Sleep latency | Unchanged/increased |
| Sleep efficiency | Decreased |
| Sleep fragmentation | Increased |
| Arousals | Increased |
| NREM stage 1 (N1) | Increased |
| NREM stage 2 (N2) | Increased |
| NREM stage 3 (N3) | Decreased |
| REM | Decreased |
| Challenges with scoring PSG in
critically ill patients | |
| NREM stage 1 and 2 | Poor interobserver reliability with R&K |
| NREM stage 2 | Difficulty classifying |
| Absence of K complexes | 20–44% |
| Absence of sleep spindles | 20–44% |
| Use of sedating medications | |
| Alternative PSG scoring
strategies | |
| Pathologic wakefulness | Visual assessment of EEG reactivity using spectral analysis with eyes open and closed |
| Atypical sleep | Absence of K complexes and sleep spindles |
| High-amplitude continuous irregular delta frequency EEG | |
| No fast frequencies, no REM | |
| Low-amplitude chin EMG | |
Definition of abbreviations: ICU = intensive care unit; NREM = non–rapid eye movement; PSG = polysomnographic; R&K = Rechtschaffen & Kales; REM = rapid eye movement; TST = total sleep time.