The impact of screen time on sleep is a well-researched topic, with evidence suggesting that excessive screen time, especially before bed, can negatively affect sleep quality and duration. Here are some key points:

1. **Blue Light Exposure**: Screens emit blue light, which can interfere with the production of melatonin, the hormone responsible for regulating sleep-wake cycles. Reduced melatonin makes it harder to fall asleep and can disrupt the quality of sleep.

2. **Delayed Sleep Onset**: Engaging with screens before bedtime, such as using smartphones, tablets, or watching TV, can delay the onset of sleep. This delay is often due to both the stimulating content and the light exposure.

3. Reduced Sleep Duration: Increased screen time, especially in the evening, is associated with shorter sleep duration. This is partly due to the delayed sleep onset and partly because engaging activities on screens can prolong the time spent awake.

4. Sleep Quality: Excessive screen time can lead to poorer sleep quality. People might experience more awakenings during the night, less deep sleep, and overall less restorative sleep.

5. Daytime Sleepiness: Poor sleep quality and reduced sleep duration can result in increased daytime sleepiness and decreased cognitive function, affecting performance at work or school.