Research
A day is not one temperature
Central Bearded Dragons warm themselves behaviourally. They may bask, move into partial shade, climb, retreat or change posture as conditions change. Controlled research confirms that they actively select temperatures rather than simply accepting the temperature around them.
Activity can therefore occur in several bursts. A dragon seen basking in the morning may become less visible through the hottest part of the day and reappear later when conditions suit it.
Research
Seasonal change
Cooler and shorter days can reduce activity and contribute to brumation. Brumation is a genuine seasonal physiological state, not merely a captive dragon choosing to sleep for longer.
Not every individual follows the same calendar or remains inactive for the same period. Location, weather, body condition, age and individual biology can all affect what is observed.