msf_sc() computes the sleep-corrected local time of mid-sleep on work-free days for standard, micro, and shift versions of the Munich ChronoType Questionnaire (MCTQ).

When using the shift version of the MCTQ, replace the value of sd_week to sd_overall, as instructed in the Arguments section.

## Usage

msf_sc(msf, sd_w, sd_f, sd_week, alarm_f)

## Arguments

msf

An hms object corresponding to the local time of mid-sleep on work-free days from a standard, micro, or shift version of the MCTQ questionnaire. You can use msl() to compute it.

sd_w

A Duration object corresponding to the sleep duration on work days from a standard, micro, or shift version of the MCTQ questionnaire. You can use sdu() to compute it.

sd_f

A Duration object corresponding to the sleep duration on work-free days from a standard, micro, or shift version of the MCTQ questionnaire. You can use sdu() to compute it.

sd_week

A Duration object corresponding to the average weekly sleep duration from a standard or micro version of the MCTQ questionnaire (you can use sd_week() to compute it) or the overall sleep duration of a particular shift from a shift version of the MCTQ questionnaire (you can use sd_overall() to compute it).

alarm_f

A logical object corresponding to the alarm clock use on work-free days from a standard, micro, or shift version of the MCTQ questionnaire. Note that, if alarm_f == TRUE, msf_sc cannot be computed, msf_sc() will return NA for these cases. For the $$\mu$$MCTQ, this value must be set as FALSE all times, since the questionnaire considers only the work-free days when the respondent does not use an alarm (e.g., alarm_f = rep(FALSE, length(msf))).

## Value

An hms object corresponding to the MCTQ chronotype or sleep-corrected local time of mid-sleep on work-free days.

## 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.

### 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 msf_sc() ($$MSF_{sc}$$) computation are as follows.

### Notes

• For all cases, $$MSF_{sc}$$ cannot be computed if the participant wakes up with an alarm clock on work-free days ($$Alarm_F$$).

• For MCTQ$$^{Shift}$$, the computation below must be applied to each shift section of the questionnaire.

• $$MSF_{sc}$$ is a proxy for the subject chronotype in standard and micro versions of the MCTQ.

• The basis for estimating chronotype in shift-workers is the mid-sleep on work-free days after evening shifts ($$MSF^E$$). In case work schedules do not comprise evening shifts, Juda, Vetter, & Roenneberg (2013) propose to derive it from the $$MSF_{sc}$$ of other shifts (e.g., by using a linear model). Unfortunately, the mctq package can't help you with that, as it requires a closer look at your data.

• $$MSF_{sc}$$ depends on developmental and environmental conditions (e.g., age, light exposure). For epidemiological and genetic studies, $$MSF_{sc}$$ must be normalized for age and sex to make populations of different age and sex compositions comparable (Roenneberg, Allebrandt, Merrow, & Vetter, 2012).

• 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

$$\textrm{If } Alarm_{F} = True \; , \; MSF_{sc} = \textrm{Not Available (NA)}$$ $$\textrm{Else if } SD_F \leq SD_W \; , \; MSF_{sc} = MSF$$ $$\textrm{Else } \; , \; MSF_{sc} = MSF - \frac{SD_F - SD_{week}}{2}$$

Where:

• $$MSF_{sc}$$ = Sleep-corrected local time of mid-sleep on work-free days.

• $$Alarm_{F}$$ = A logical value indicating if the respondent uses an alarm clock to wake up on work-free days.

• $$MSF$$ = Local time of mid-sleep on work-free days.

• $$SD_W$$ = Sleep duration on workdays.

• $$SD_F$$ = Sleep duration on work-free days.

• $$SD_{week}$$ = Average weekly sleep duration.

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

Note that, since:

$$MSF = SO_{F} + \frac{SD_{F}}{2}$$

Where:

• $$MSF$$ = Local time of mid-sleep on work-free days.

• $$SO_{F}$$ = Local time of sleep onset on work-free days.

• $$SD_{F}$$ = Sleep duration on work-free days.

The last condition of the $$MSF_{sc}$$ computation can be simplified to:

$$MSF_{sc} = SO_{F} + \frac{SD_{F}}{2} - \frac{SD_{F} - SD_{week}}{2}$$ $$MSF_{sc} = SO_{F} + \frac{SD_{F}}{2} - \frac{SD_{F}}{2} + \frac{SD_{week}}{2}$$ $$MSF_{sc} = SO_{F} + \frac{SD_{week}}{2}$$

### For the shift version of the MCTQ

$$\textrm{If } Alarm_{F}^{M/E/N} = True \; , \; MSF_{sc}^{M/E/N} = \textrm{Not Available (NA)}$$ $$\textrm{Else if } SD_{F}^{M/E/N} \leq SD_{W}^{M/E/N} \; , \; MSF_{sc}^{M/E/N} = MSF^{M/E/N}$$ $$\textrm{Else } \; , \; MSF_{sc}^{M/E/N} = MSF^{M/E/N} - \frac{SD_{F}^{M/E/N} - \emptyset SD^{M/E/N}}{2}$$

Where:

• $$MSF_{sc}^{M/E/N}$$ = Sleep-corrected local time of mid-sleep between two free days after a particular shift.

• $$Alarm_{F}^{M/E/N}$$ = A logical value indicating if the respondent uses an alarm clock to wake up between two free days after a particular shift.

• $$MSF^{M/E/N}$$ = Local time of mid-sleep between two free days after a particular shift.

• $$SD_{W}^{M/E/N}$$ = Sleep duration between two days in a particular shift.

• $$SD_{F}^{M/E/N}$$ = Sleep duration between two free days after a particular shift.

• $$\emptyset SD^{M/E/N}$$ = Overall sleep duration of a particular shift.

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

Note that, since:

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

Where:

• $$MSF^{M/E/N}$$ = Local time of mid-sleep between two free days after a particular shift.

• $$SO_{F}^{M/E/N}$$ = Local time of sleep onset between two free days after a particular shift.

• $$SD_{F}^{M/E/N}$$ = Sleep duration between two free days after a particular shift.

The last condition of the $$MSF_{sc}^{M/E/N}$$ computation can be simplified to:

$$MSF_{sc}^{M/E/N} = SO_{F}^{M/E/N} + \frac{SD_{F}^{M/E/N}}{2} - \frac{SD_{F}^{M/E/N} - \emptyset SD^{M/E/N}}{2}$$ $$MSF_{sc}^{M/E/N} = SO_{F}^{M/E/N} + \frac{SD_{F}^{M/E/N}}{2} - \frac{SD_{F}^{M/E/N}}{2} + \frac{\emptyset SD^{M/E/N}}{2}$$ $$MSF_{sc}^{M/E/N} = SO_{F}^{M/E/N} + \frac{\emptyset SD^{M/E/N}}{2}$$

## 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/

Other MCTQ functions: fd(), gu(), le_week(), msl(), napd(), sd24(), sd_overall(), sd_week(), sdu(), sjl_sc(), sjl_weighted(), sjl(), so(), tbt()

## Examples

## Scalar example

msf <- hms::parse_hms("04:00:00")
sd_w <- lubridate::dhours(6)
sd_f <- lubridate::dhours(7)
sd_week <- lubridate::dhours(6.29)
alarm_f <- FALSE
msf_sc(msf, sd_w, sd_f, sd_week, alarm_f)
#> 03:38:42
#> 03:38:42 # Expected

msf <- hms::parse_hm("01:00:00")
sd_w <- lubridate::dhours(5.5)
sd_f <- lubridate::dhours(9)
sd_week <- lubridate::dhours(6.75)
alarm_f <- FALSE
msf_sc(msf, sd_w, sd_f, sd_week, alarm_f)
#> 23:52:30
#> 23:52:30 # Expected

msf <- hms::parse_hms("05:40:00")
sd_w <- lubridate::dhours(7.5)
sd_f <- lubridate::dhours(10)
sd_week <- lubridate::dhours(8.5)
alarm_f <- TRUE
msf_sc(msf, sd_w, sd_f, sd_week, alarm_f)
#> NA
#> NA # Expected (msf_sc cannot be computed if alarm_f == TRUE)

## Vector example

msf <- c(hms::parse_hms("03:45:00"), hms::parse_hm("04:45:00"))
sd_w <- c(lubridate::dhours(9), lubridate::dhours(6.45))
sd_f <- c(lubridate::dhours(5), lubridate::dhours(10))
sd_week <- c(lubridate::dhours(8.5), lubridate::dhours(9.2))
alarm_f <- c(FALSE, FALSE)
msf_sc(msf, sd_w, sd_f, sd_week, alarm_f)
#> 03:45:00
#> 04:21:00
#> 03:45:00 # Expected
#> 04:21:00 # Expected

## Rounding the output at the seconds level

msf <- hms::parse_hms("05:40:00")
sd_w <- lubridate::dhours(5.43678)
sd_f <- lubridate::dhours(9.345111)
sd_week <- lubridate::dhours(7.5453)
alarm_f <- FALSE
msf_sc(msf, sd_w, sd_f, sd_week, alarm_f)
#> 04:46:00.3402
#> 04:46:00.3402 # Expected

mctq:::round_time(msf_sc(msf, sd_w, sd_f, sd_week, alarm_f))
#> 04:46:00
#> 04:46:00 # Expected