Hours of daylight in Viseu on the 15th of each month, 2026:
Hours of daylight per month in Viseu. Longest and shortest months highlighted.
Month
Daylight
Sunrise
Sunset
January
9h 35m
07:54
17:29
February
10h 40m
07:27
18:07
March
11h 54m
06:45
18:38
April
13h 17m
06:54
20:11
May
14h 26m
06:16
20:42
June
15h 04m
06:01
21:05
July
14h 49m
06:14
21:02
August
13h 49m
06:43
20:32
September
12h 30m
07:13
19:43
October
11h 10m
07:43
18:53
November
9h 56m
07:19
17:15
December
9h 17m
07:49
17:06
Why the daylight swing runs your mornings
On the shortest days Viseu gets only about 9h 17m of light. Daylight is the master input to your body clock. Less of it — arriving later and leaving earlier — means your internal timing gets a weaker, later signal, so you drift toward waking in the dark. That is why the same alarm is trivial in June and merciless in December. It is a light problem, not a discipline problem — here is how to use light to fix it, and how to wake up when it is still dark out.
It ranges from about 15h 04m at the longest point of the year (June) down to about 9h 17m at the shortest (December) — a swing of roughly 5h 47m. The chart and table on this page break it down month by month.
When is the shortest day in Viseu?
Around the winter solstice in December, with roughly 9h 17m of daylight. That is also when mornings are darkest and waking up is hardest.
Does less daylight actually affect sleep and energy?
Yes. Shorter days mean less light to anchor your circadian rhythm, which can flatten your energy, shift your sleep later, and for some people contributes to seasonal low mood. Getting outside early — even briefly — is one of the most effective countermeasures. If low mood is persistent, that is worth raising with a doctor; this is general information, not a diagnosis.
Why is it hardest to get up on the shortest days?
Because your alarm fires while it is still dark, before any daylight has reached your eyes to shut off melatonin and start the cortisol rise that makes you feel awake. Biologically it is still night, so the same wake-up time that is easy in summer feels brutal in winter.
Why people use Captain Wake to wake up on time
Not because it rings louder. Because it removes every way your half-asleep brain talks you back into bed.
1
There is no button to tap
Swiping an alarm away is a reflex you can perform while still asleep. A mission needs your thinking brain switched on — and once it is on, sinking back under is much harder.
2
It survives every trick
Force-quit the app, restart the phone, flip it to silent, turn the volume down. The alarm re-arms and keeps going until the mission is actually done.
3
It gets you physically upright
Photo and barcode missions are anchored to a spot in another room, so the only way to stop the noise is to stand up and walk there. You cannot pre-stage it from bed.
4
It fixes the night, not just the morning
A sleep forecast before bed, bedtime reminders and wake-up streaks — because the 6 AM problem usually starts at 1 AM.
Short days, dark mornings — the alarm that still gets you up.
Captain Wake keeps ringing until you complete a real-world mission. No snooze, no swipe-and-sleep.
