... Peo- ple who display a temperature difference of less than 1 C are short sleepers and those who display larger differences (>1 C) are long sleepers. ... Perlapine [1977-11-3], 6-(4-methyl-1-piper- azinyl)-11 H-dibenz [b,e] azepine, C19H21N2, Mr 291.40, mp 136 – 138 C. ...