Compute MCTQ local time of mid-sleep

msl() computes the local time of mid-sleep for standard, micro, and shift versions of the Munich ChronoType Questionnaire (MCTQ).

Please note that, although we tried to preserve the original authors' naming pattern for the MCTQ functions, the name ms provokes a dangerous name collision with the ms() function (a function for parsing minutes and seconds components). That's why we named it msl. msl() and sdu() are the only exceptions, all the other mctq functions maintain a strong naming resemblance with the original authors' naming pattern.

Usage

msl(so, sd)

Arguments

so: An hms object corresponding to the local time of sleep onset from a standard, micro, or shift version of the MCTQ questionnaire. You can use so() to compute it for the standard or shift version.
sd: A Duration object corresponding to the sleep duration from a standard, micro, or shift version of the MCTQ questionnaire. You can use sdu() to compute it for any MCTQ version.

Value

An hms object corresponding to the vectorized sum of so and (sd / 2) in a circular time frame of 24 hours.

Details

Standard MCTQ functions were created following the guidelines in Roenneberg, Wirz-Justice, & Merrow (2003), Roenneberg, Allebrandt, Merrow, & Vetter (2012), and from The Worldwide Experimental Platform (theWeP, n.d.).

$\mu$MCTQ functions were created following the guidelines in Ghotbi et al. (2020), in addition to the guidelines used for the standard MCTQ.

MCTQ$^{Shift}$ functions were created following the guidelines in Juda, Vetter, & Roenneberg (2013), in addition to the guidelines used for the standard MCTQ.

See the References section to learn more.

Class requirements

The mctq package works with a set of object classes specially created to hold time values. These classes can be found in the lubridate and hms packages. Please refer to those package documentations to learn more about them.

Rounding and fractional time

Some operations may produce an output with fractional time (e.g., "19538.3828571429s (~5.43 hours)", 01:15:44.505). If you want, you can round it with mctq:::round_time().

Our recommendation is to avoid rounding, but, if you do, make sure that you only round your values after all computations are done. That way you avoid round-off errors.

Guidelines

Roenneberg, Allebrandt, Merrow, & Vetter (2012), Ghotbi et al. (2020), Juda, Vetter, & Roenneberg (2013), and The Worldwide Experimental Platform (n.d.) guidelines for msl() ($MSW$ or $MSF$) computation are as follows.

Notes

This computation must be applied to each section of the questionnaire.
If you are visualizing this documentation in plain text, you may have some trouble understanding the equations. You can see this documentation on the package website.

For standard and micro versions of the MCTQ

$$MS_{W/F} = SO_{W/F} + \frac{SD_{W/F}}{2}$$

Where:

$MS_{W/F}$ = Local time of mid-sleep on work or work-free days.
$SO_{W/F}$ = Local time of sleep onset on work or work-free days.
$SD_{W/F}$ = Sleep duration on work or work-free days.

* $W$ = Workdays; $F$ = Work-free days.

For the shift version of the MCTQ

$$MS_{W/F}^{M/E/N} = SO_{W/F}^{M/E/N} + \frac{SD_{W/F}^{M/E/N}}{2}$$

Where:

$MS_{W/F}^{M/E/N}$ = Local time of mid-sleep between two days in a particular shift or between two free days after a particular shift.
$SO_{W/F}^{M/E/N}$ = Local time of sleep onset between two days in a particular shift or between two free days after a particular shift.
$SD_{W/F}^{M/E/N}$ = Sleep duration between two days in a particular shift or between two free days after a particular shift.

* $W$ = Workdays; $F$ = Work-free days, $M$ = Morning shift; $E$ = Evening shift; $N$ = Night shift.

References

Ghotbi, N., Pilz, L. K., Winnebeck, E. C., Vetter, C., Zerbini, G., Lenssen, D., Frighetto, G., Salamanca, M., Costa, R., Montagnese, S., & Roenneberg, T. (2020). The $\mu$MCTQ: an ultra-short version of the Munich ChronoType Questionnaire. Journal of Biological Rhythms, 35(1), 98-110. doi:10.1177/0748730419886986

Juda, M., Vetter, C., & Roenneberg, T. (2013). The Munich ChronoType Questionnaire for shift-workers (MCTQ$^{Shift}$). Journal of Biological Rhythms, 28(2), 130-140. doi:10.1177/0748730412475041

Roenneberg T., Allebrandt K. V., Merrow M., & Vetter C. (2012). Social jetlag and obesity. Current Biology, 22(10), 939-43. doi:10.1016/j.cub.2012.03.038

Roenneberg, T., Wirz-Justice, A., & Merrow, M. (2003). Life between clocks: daily temporal patterns of human chronotypes. Journal of Biological Rhythms, 18(1), 80-90. doi:10.1177/0748730402239679

The Worldwide Experimental Platform (n.d.). MCTQ. https://www.thewep.org/documentations/mctq/

Examples

## Scalar example

so <- hms::parse_hm("23:30")
sd <- lubridate::dhours(8)
msl(so, sd)
#> 03:30:00
#> 03:30:00 # Expected

so <- hms::parse_hm("01:00")
sd <- lubridate::dhours(10)
msl(so, sd)
#> 06:00:00
#> 06:00:00 # Expected

so <- hms::as_hms(NA)
sd <- lubridate::dhours(7.5)
msl(so, sd)
#> NA
#> NA # Expected

## Vector example

so <- c(hms::parse_hm("00:10"), hms::parse_hm("01:15"))
sd <- c(lubridate::dhours(9.25), lubridate::dhours(5.45))
msl(so, sd)
#> 04:47:30
#> 03:58:30
#> [1] 04:47:30 # Expected
#> [1] 03:58:30 # Expected