Write where you're stuck. Sleep. Read the note first thing.

Work seriously on a stuck problem in the evening, write where you're stuck, sleep, and look at the note before anything else in the morning. People who slept were far more likely to find a hidden shortcut. Ten minutes of quiet rest does a similar job.
P Evidence: promising. Good studies, but small or few. Use it and keep checking.
Wagner et al. 2004 (Nature) and a later extension.
Not medical, legal or financial advice.
In The Ecosystem every framework comes with a daily action, a room that checks in, and the full library.