The Multiple Sleep Latency Test: Individual Variability and Time of Day Effect in Normal Young Adults

Abstract

The influence of individual characteristics on diurnal physiological sleep tendency was investigated in young good sleepers. Fifty-five subjects underwent a Multiple Sleep Latency Test (MSLT) procedure. Among them 11 also participated in Repeated Test Sustained Wakefulness (RTSW) procedure. The MSLT results were analyzed as a function of both the number of sleep onsets per day and the time of day. Diurnal sleepiness seemed to be better appreciated by sleep onset (SO) frequency than by the traditional criteria of sleep latency. SO frequency, unlike latency, was influenced by factors such as usual sleep duration, morning/evening score, and RTSW procedure. Time of day effect was characterized by a decrease in sleep tendency at the beginning and at the end of the day (decrease in SO frequency and increase in SO latencies); between these two points a peak of sleepiness around 1400 was observed. The morning and evening periods of high alertness could represent important anchor points for the coupling of the sleep/wake and temperature rhythms.

Time‐of‐day variations in different measures of sleepiness (MSLT, pupillography, and SSS) and their interrelations

“…This observation corresponds well to the known pattern of time-of-day variation of sleep tendency~propensity!~Clodoré, Benoit, Foret, & Bouard, 1990;Lavie, 1986; 1991!. The high sleep latency in the evening hours corresponds to what Lavie~1986!…”

The 5-min pupillary alertness test is sensitive to modafinil: a placebo controlled study in patients with sleep apnea

“…1 top left). This is consistent with a mid-afternoon circadian nadir in the levels of alertness, which has previously been demonstrated in both patient and control groups with the MSLT (Clodore et al 1990) and pupillometry (Bitsios et al 2006;Merritt et al 1998). Modafinil reversed this circadian effect on pupil size as evidenced by the significant treatment effect.…”

On the Choice of Recording Duration in Pharmaco-EEG Studies

“…If the two decision criteria, namely (1) dif ferential sensitivity of RT and RS, and (2) reliability are both taken into consideration, then the normally used 5-min recording duration is an optimal choice for PEEG recordings. If, however, the aim of the study is to measure the transition time from the wake state into sleep, then a different method should be applied such as, for example, the multiple sleep latency test [ 10,11], For the vigilance control, which was assured in our recording by a choice reaction paradigm, alternative tech niques have been proposed such as, for example (1) arous ing the subject if EEG signs of a vigilance decrease are seen by the supervising technician [ 12]; (2) buzzer control [ 13], and (3) verbal/cognitive tasks, such as constructing a story based on a few key words presented just before the recording session [14], The choice of the recording dura tion will then depend critically on the degree of involve ment demanded by the specific technique used to control the subjects' vigilance state.…”