Final answer:
Monica's struggle to stay alert at work is likely due to an interruption of her circadian rhythm, which regulates sleep-wake patterns. Bright light therapy can help manage circadian disruptions.
Step-by-step explanation:
Monica's struggle to stay alert at work is probably due to an interruption of her usual circadian rhythm. Circadian rhythms are biological cycles that regulate our sleep-wake patterns and are typically aligned with our external environment. When people experience disruptions to their circadian rhythms, such as working night shifts or traveling across time zones, it can lead to difficulties with alertness and sleepiness. Bright light therapy can be helpful in managing circadian disruptions.