The line in the Sleep view is not a trendline. It is just a plot of data points. It looks like one value for each day.
What do you mean by "sharper"?
Also, the CPU Utilization chart does not show a trendline either. It is also just a plot of data, but much denser.
If you want a trendline, then you have to add a trendline to the chart. You will have to decide how you want to model the trend (i.e., linear, quadratic, logarithmic).
What analysis do you want to do on this data? What are you trying to depict or learn from the chart? That way we can help identify the correct method to do that.
This is what a trendline looks like: