The calculation
Light while we’re awake
The clock does not change the length of the day. It changes when the sun rises and sets, and therefore how much of the day falls while we sleep. Here is the count, day by day, using Quebecers’ sleep hours.
Morning −127 h
Afternoon and evening +360 h
With daylight time, in total +233 h of light a year while we’re awake
The daylight time gain, month by month (hours)
- 10 Jan.
- 13 Feb.
- 19 Mar.
- 24 Apr.
- 26 May
- 26 June
- 27 July
- 25 Aug.
- 21 Sept.
- 18 Oct.
- 13 Nov.
- 10 Dec.
Average per person, based on the sleep hours reported by Quebecers to Statistics Canada12. We assume people sleep at the same clock times whichever time is chosen. This is available light, not time spent outdoors.
Town by town
Hours of light per person per year, while awake.
| Town | Standard time | Today (clock changes) | Daylight time | Daylight time gain |
|---|---|---|---|---|
| Montréal | 3,736 h | 3,919 h | 3,969 h | +233 h |
| Québec City | 3,693 h | 3,880 h | 3,933 h | +241 h |
| Laval | 3,739 h | 3,921 h | 3,971 h | +232 h |
| Gatineau | 3,773 h | 3,950 h | 3,997 h | +224 h |
| Longueuil | 3,734 h | 3,916 h | 3,967 h | +233 h |
| Sherbrooke | 3,707 h | 3,893 h | 3,946 h | +240 h |
| Saguenay | 3,688 h | 3,876 h | 3,927 h | +239 h |
| Lévis | 3,693 h | 3,881 h | 3,934 h | +241 h |
| Trois-Rivières | 3,717 h | 3,902 h | 3,953 h | +236 h |
| Drummondville | 3,717 h | 3,902 h | 3,954 h | +237 h |
| Saint-Georges | 3,684 h | 3,873 h | 3,928 h | +244 h |
| Rimouski | 3,642 h | 3,835 h | 3,891 h | +249 h |
| Rouyn-Noranda | 3,823 h | 3,991 h | 4,030 h | +207 h |
| Val-d’Or | 3,803 h | 3,975 h | 4,015 h | +212 h |
| Baie-Comeau | 3,634 h | 3,828 h | 3,883 h | +249 h |
| Sept-Îles | 3,600 h | 3,797 h | 3,854 h | +254 h |
| Matane | 3,623 h | 3,818 h | 3,875 h | +252 h |
| Gaspé | 3,566 h | 3,766 h | 3,828 h | +262 h |
All 1,190 municipalities are calculated: look up yours.
How it is calculated
The sun
For each day of the year, we calculate the time of sunrise and sunset (the NOAA method3, clear horizon), on standard time (UTC−5), on daylight time (UTC−4) and with the current clock changes.
Sleep
Statistics Canada’s 2022 Time Use Survey asks thousands of people to record everything they do over 24 hours1. From the answers of 2,343 Quebecers, we get, for each five-minute slot, the share of people who are not asleep, by season and by weekday or weekend.
The count
Each five-minute slot when the sun is up counts for the share of Quebecers awake at that moment. On a spring weekday morning, at 5 AM, 16% of Quebecers are up; at 9 PM, 88%. An hour of sunshine at 5 AM therefore benefits far fewer people than an hour at 9 PM. We add it all up over the year: that is the daylight available while awake, per person.
What this figure doesn’t say
- We assume people sleep at the same clock times, whichever time is chosen. If everyone shifted their sleep, work and school by an hour with the sun, the gain would disappear.
- It is available light, not time spent outdoors, nor a dose of light received, nor a health effect. An hour of light in the morning does not act on the body clock the way an hour in the evening does.
- The gain depends on the comparison. Compared with today’s clock changes, it is smaller (+50 h in Montréal): we already live on daylight time from spring to fall. The choice now on the table is between daylight time and standard time, both all year.
- The sleep hours are those of Québec as a whole, reported in 2022 and 2023 by people aged 15 and over. They are not measured town by town; only the sun’s times change from one town to another.
- It is an original calculation by Ma lumière, not an official Statistics Canada statistic, and it has not been peer-reviewed. Using the waking profiles published below, anyone can redo the calculation; an independent audit reproduced it. The extraction of these profiles from the microdata, however, has not yet been verified independently.
The data
Download the waking profiles (CSV, 288 five-minute slots). These are aggregated proportions, with no individual data, drawn from Statistics Canada’s public use microdata file14.
Your turn
Québec is deciding now.
MNAs will vote. Two minutes is all it takes to tell them you want to keep daylight saving time all year.