Sleep scientist Matthew Walker says sleep deficiency is associated with problems with concentration, memory and the immune system — as well as with shorter lifespans. Walker discusses the effects of caffeine, alcohol and sleeping pills, and also offers some tips to help you sleep better. His book, ‘Why We Sleep,’ is now out in paperback. (Originally broadcast October 2017) Also, film critic Justin Chang reviews ‘Sorry to Bother You’ and ‘Blindspotting.‘