My pets had an expectation of events to happen at specific times.
Dog would sit by the door and 'expect' to see $family_member arrive home from school/work. (noteworthy for those that had regular schedule and always got home about the same time.)
My last cat expected to be fed at the same time every day.
For the first couple of years I had my cat, my job & routine were identical every day. Wake at 6am, feed cat, goto work.
On weekends this bothered the cat so he would wake me up at 6:01 so he could get his food. I hated that he would never let me sleep in.
Fast-forward a few months to the daylight-savings change; and then at 5:01 he started expecting food. The damn cat had an internal clock that was very accurate.
So I am sure a lot of animals have internal clocks and don't solely rely on "% of sunlight" to determine behaviour.
There is some speculation that dogs use their sense of smell to determine the passage of time. The theory is that when an owner's scent diminishes to a certain point they know that the owner will soon be back. Dogs that normally wait at the door or at a window can be tricked by the reintroduction of the owner's smell and will fail to get ready for the event.
Not sure where you are located but there was a documentary last night on bbc which demonstrated they can’t. Do you have examples where someone has been able to do this?
A very big part of the sleep-awake cycle is regulated by the circadian rhythm, that is an automatic 24-hour cycle in animals, plants, ... https://en.wikipedia.org/wiki/Circadian_rhythm
It doesn't need light to work. (But light modifies it so after a few days it is synchronized with the local light-darkness cycle.)
So probably all the nocturnal animals that were sleeping in a dark shelter during the day missed the event.
It will probably depend on how noticeable the change is. Sleep/wake cycles are broadly controlled by internal clocks whose timing is synced to day/night cycles via light sensing cells different from those we use to see with.
From personal experience, though, most of us probably know that a bright light in the middle of the night can wake is even if we are nowhere near the point in our circadian cycle where we would be waking up. But a dim light, like a candle, probably won't.
So, I'd expect nocturnal animals in places that are already fairly dark, such as bats that live in caves, to probably sleep right through it, because it will only make a minor change to the light in the cave. Nocturnal animals that live in more exposed places might react, either to the change in light or to the change in temperature.
A bit of Googling indicates this may indeed be the case. Cave bats usually don't react. Forest dwelling bats have been seen to come out.
It would be interesting to do some experiments to see if it is the change in light or the change in temperature that is waking them.
