Final answer:
The last 2 hours of sleep are considered vital due to the benefits of REM sleep and its impact on learning and emotional processing. Insufficient sleep can result in a detrimental sleep debt, affecting cognitive functions and health.
Step-by-step explanation:
Experts suggest that the last 2 hours of sleep are quite valuable, possibly due to the preponderance of Rapid Eye Movement (REM) sleep during this time, which is associated with learning, memory consolidation, and emotional processing. The importance of these final hours resonates with the findings that optimal sleep is linked to various cognitive benefits, including enhanced creative thinking, language learning, and improved inferential judgment. Insufficient sleep leads to a sleep debt, which adversely affects alertness and mental efficiency. Ensuring optimal sleep is thus crucial for maintaining good cognitive function and overall health.