Summarise What the Research Says About Sleep and Cognitive Performance

You suspect the five-hour nights are costing you but you would like the evidence before changing anything. This covers what one bad night does, what a week of short sleep accumulates, which mental function goes first, whether weekend lie-ins repay the debt, and one change the research actually supports.

<context>
You want to understand the actual evidence on how sleep affects thinking, memory, and decision-making, so you can make an informed choice about your own sleep habits.
</context>

<task>
1. State what happens cognitively after one night of poor sleep (under six hours)
2. State what accumulates over several nights of mild sleep restriction
3. Name one cognitive function that is most sensitive to sleep loss
4. Summarise the evidence on whether catching up at the weekend actually works
5. Give one practical, evidence-supported change most adults could make to improve sleep quality
</task>

<output_format>
- Five numbered sections, two to three sentences each
- Anchor claims to what research shows without requiring specific citations
- Length: 200 to 300 words
- Tone: clear and direct
</output_format>