Adrenal glands producing too much adrenaline possibly reducing the amount of melatonin
Explanation:
Melatonin is the the hormone which is produced in the pineal gland which is found in the brain. If something scares you in the night, it is likely that the amount of adrenaline has been causing you to fight or flight the response.
Explanation: flight is energy expensive. Cormorants in a remote archipelago don’t have anywhere to fly to. Natural selection favours energy efficiency.