I'm interested in the sleep patterns of wild animals, that still use sun for controlling their biological clock.
Animals entrain their biological clock to the day/night cycle using light as the entrainment signal. The biological clock follows the day/night cycle: dim light initiates melatonin secretion, while bright morning light stops melatonin production. Melatonin is involved in sleep regulation
Here, I have plotted the day duration over the course of the year for Northeast US, around Washington DC.
My question is given the day duration plot below, would the total sleep duration for wild animals vary over the course of the year?
In other words, would animals sleep longer in the winter time and shorter in the summer time?