Identical twins have more similar sleep patterns than do fraternal twins, and people in industrialized nations go to bed later at night than their counterparts of a century ago. These facts best illustrate that sleep patterns are affected by both

These facts best illustrate that sleep patterns are affected by both "heredity and environment".

The most persuading information originates from the investigations of twins. Identical twins, regardless of whether not raised together, have more comparable sleep patterns and qualities than non-identical twins. In any case, these same examinations additionally demonstrate that condition assumes an extensive job in some rest/wake factors.