Psychomotor Vigilance Test and Its Association With Daytime Sleepiness and Inflammation in Sleep Apnea: Clinical Implications, 2017, Li et al.

[nataliezzz]

Psychomotor Vigilance Test and Its Association With Daytime Sleepiness and Inflammation in Sleep Apnea: Clinical Implications
Yun Li, Alexandros Vgontzas, Ilia Kritikou, Julio Fernandez-Mendoza, Maria Basta, Slobodanka Pejovic, Jordan Gaines, Edward O Bixler
https://pmc.ncbi.nlm.nih.gov/articles/PMC5566460/ (PDF available)

Study objectives: Excessive daytime sleepiness (EDS) is a key symptom of obstructive sleep apnea (OSA). The Psychomotor Vigilance Task (PVT) has been suggested as an objective easy-to-use, inexpensive alternative to the Multiple Sleep Latency Test (MSLT) to measure EDS. In patients with OSA, physiological sleepiness, but not subjective EDS (Epworth Sleepiness Scale [ESS]), has been associated with increased levels of the sleep-inducing proinflammatory cytokine interleukin-6 (IL-6). The goal of this study was to assess the association of PVT with objectively measured sleepiness (MSLT) and subjectively measured sleepiness (ESS) and IL-6 levels in patients with OSA.

Methods: We studied 58 untreated patients with OSA who underwent an 8-hour in-laboratory polysomnography for 4 consecutive nights. MSLT, PVT, and 24-hour serial profiles of IL-6 were assessed on the fourth day. PVT variables included number of lapses, mean reciprocal of the fastest 10% and slowest 10% reaction times, and median of 1/reaction time. ESS was assessed on day 1 of the study.

Results: Higher ESS scores were significantly associated with greater number of lapses (β = .34, P = .02) and lower values of 1/RT (β = -.36, P = .01) and slowest 10% RTs (β = -.30, P = .04). No significant association was observed between PVT and MSLT, nor PVT and IL-6 levels.

Conclusions: Our findings suggest that PVT is associated with subjectively assessed daytime sleepiness, but not with physiological sleepiness nor IL-6 levels in patients with OSA. It appears that ESS and PVT may be useful in predicting risks associated with impaired performance, such as traffic accidents, in patients with OSA.

 

[forestglip]

Responding to a question about this paper from a different thread.

But it is interesting that objective sleepiness (MSLT) is not associated with decreased psychomotor vigilance, as it seems like it would be, right?

It does seem like if someone is sleep-deprived and thus falls asleep faster, one would expect to see impairments in sustained attention tasks. It might be too small a sample, and too much noise due to other causes of impaired sustained attention, such as non-sleepiness fatigue, or the other things they mention:

It has been reported that performance in neurobehavioral tests, such as PVT, is influenced by several factors, such as anxiety, depression, motivation, and boredom.

 

[nataliezzz]

It does seem like if someone is sleep-deprived and thus falls asleep faster, one would expect to see impairments in sustained attention tasks. It might be too small a sample, and too much noise due to other causes of impaired sustained attention, such as non-sleepiness fatigue, or the other things they mention:

It was hypothesized below why OSA patients with purely objective sleepiness don't have impaired psychomotor vigilance. I'm not sure that "sleep deprivation" in the traditional sense really comes into play here much at all (there does appear to be a contribution to objective sleepiness likely driven by cumulative sleep fragmentation related to apnea/hypopnea-related arousals once you get to an AHI > ~45, though it seems modest - and you can see that there are still people with an AHI >45 awake at 10 and 20 minutes into the MSLT).

So basically, in the purely objectively sleepy OSA phenotype (which one would expect to report subjective sleepiness and to be more impaired in terms vigilance etc.) the increased "sympathetic drive" - i.e. sympathetic nerve activity (SNA) as measured by 24-hour urine norepinephrine - may actually counteract subjective sleepiness and decreased alertness/vigilance.

Additionally, in this study, EEG changes induced by sustained inspiratory flow limitation (the putative driver of symptoms for OSA "Phenotype 2" patients - those with subjective excessive daytime sleepiness /fatigue) were not associated with changes in objective sleepiness (MSLT), only PVT lapses, again reinforcing the dissociation between objective sleepiness and psychomotor vigilance and supporting that impaired psychomotor vigilance is likely primarily associated with OSA/UARS "Phenotype 2."