Yes, Wolf is 100% correct. Let me elaborate a bit further so you can understand the mechanics of it. A bird endocrine system is photoperiodic, as Wolf said, and that means that their body registers the time difference between seasons - this is done so very exactly that tropical birds (and all other birds) are able to register a difference of a mere 20 minutes (which is the difference in the tropics -it's not 12 hours of light and 12 hours of darkness, it's 11:40 hours of light and 12:20 hours of dark or 12:20 of light and 11:40 of darkness). BUT their main breeding trigger is food availability instead of the length of dayhours so they only breed when food is abundant (usually at the beginning of the dry season when everything sprouts after the rainy season -which also has weather not propitious for breeding). The problem with this is that, in captivity, the weather is always good and the food is always rich and plentiful so, if you keep a parrot at 12 hours of light and 12 of dark, the parrot will produce sexual hormones all year round, year after year after year. Thankfully, all tropical birds revert to photoperiodism as their main trigger when exposed to longer differences which is great for us, parrot keepers, because producing sexual hormones all the time is something that 1) never happens in Nature (birds have a 'resting' season when they don't breed) and 2) creates physical problems because Nature made it so birds sexual organs are dormant and small during the resting season until the breeding trigger acts and they start producing sexual hormones which make their gonads (sexual organs) active and large. When you keep a bird producing sexual hormones without rest, these organs can become hugely enlarged, pushing other organs from their rightful place and causing chronic pain.
Now, in order for a bird to mark the time when the day starts and ends (so the body can determine whether it's time to produce sexual hormones or not), it needs to be exposed to dawn and dusk because it's the change in light spectrum that turns the 'clock' on and off. And that's why exposing the bird to 12 hours of dark and 12 of light all year round is bad and why you can't just arbitrarily choose the time the parrot wakes up or goes to bed. You need to follow the sun.