Final answer:
Limited exposure to natural light is related to shorter sleep durations in early childhood, as it disrupts the circadian rhythm. Positive sleep practices like consistency in bedtime routines and regular sleep schedules contribute to better sleep hygiene and longer sleep duration. The correct option is 2.
Step-by-step explanation:
The factor related to shorter sleep durations in early childhood is Limited exposure to natural light. A consistent bedtime routine and following a regular sleep schedule are practices that support good sleep hygiene and contribute to longer, more restful sleep patterns.
High levels of parental involvement during bedtime can also be beneficial in establishing a consistent sleep routine. It is the reduced exposure to natural light which disrupts the circadian rhythm that is more likely to be associated with shorter sleep duration in children.
Circadian rhythms, regulated by the suprachiasmatic nucleus (SCN), are vital for aligning our biological clock with our environment, and light is a major cue in this regulation.
To improve sleep quality and duration, it's important to cultivate healthy sleep practices, such as keeping a sleep schedule and avoiding stimulating activities before bedtime. The correct option is 2.