Predicting duration of sleep from the three process model of regulation of alertness.
OBJECTIVE
Irregular working hours severely disturb sleep and wakefulness. This paper presents a modification of the quantitative (computerised) three process model of regulation of alertness to predict duration of sleep in connection with irregular sleep patterns.


METHODS
The model uses a circadian "C" (sinusoidal) and homeostatic "S" (exponential) component (the duration of previous periods awake and asleep), which are summed to yield predicted alertness (on a scale of 1-16). It assumes that waking from sleep will occur at a given alertness level (S' + C') when recuperation is complete. Variables of electroencephalographic duration of sleep from two studies of irregular sleep were used to model the S and C variables in a regression approach to maximise prediction. The model performance was cross validated against published field and laboratory data.


RESULTS
The model parameters were defined with a high degree of precision R2 = 0.99 and the validation yielded similar values R2 = 0.98-0.95, depending on the acrophase. The paper also describes a simplified graphical version of the computation model seen as a two dimensional duration of sleep nomogram.


CONCLUSIONS
The model seems to predict group means for duration of sleep with high precision and may serve as a tool for evaluating work and rest schedules to reduce risks of sleep disturbances.
Akerstedt
T
T
Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden.
Folkard
S
S
D000328:Adult; D002940:Circadian Rhythm; D006706:Homeostasis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D017286:Polysomnography; D012044:Regression Analysis; D012890:Sleep; D013997:Time Factors; D014851:Wakefulness; D014940:Work Schedule Tolerance