Allowing ad libitum sleep during overnight polysomnography affects Multiple Sleep Latency Test results in patients...

The Multiple Sleep Latency Test (MSLT) is a key diagnostic component in the diagnosis of central disorders of hypersomnolence. Due to time constraints, it is common practice to wake patients at a standard time from overnight polysomnography (PSG) prior to the MSLT. This has the potential to influence MSLT results due to sleep deprivation. We describe the impact of allowing ad libitum sleep on the night prior to the MSLT in patients being assessed for hypersomnolence.

A total of 580 consecutive patients undergoing PSG/MSLT for assessment of hypersomnolence were analyzed: 290 either side of a change in laboratory protocol that allowed patients ad libitum sleep during the PSG, rather than being woken at a prespecified time. Baseline characteristics, PSG and MSLT results were compared between the groups.

Groups were similar at baseline, other than there being more females in the ad libitum group. After adjusting for confounding variables, patients allowed ad libitum sleep had later sleep offset time (+58.7 minutes; P < .001), longer PSG total sleep time (+47.8 minutes; P < .001), longer MSLT mean sleep latency (+1.3 minutes; P = .002), and 23% fewer MSLT with mean sleep latency less than 8 minutes (P = .004) when compared with patients who were woken at a standard time.

The common practice of waking patients from their PSG at a standard time has the potential to curtail sleep and affect MSLT results by reducing mean sleep latency. Patients being assessed for hypersomnolence should be allowed ad libitum sleep during the PSG on the night prior to their MSLT.

Frenkel S, Amaranayake A, Molesworth C, Orellana L, Southcott AM. Allowing ad libitum sleep during overnight polysomnography affects Multiple Sleep Latency Test results in patients being assessed for hypersomnolence. J Clin Sleep Med. 2024;20(12):1937-1943.