Are humans the only animals who sleep in 1 block of time? i have heard some animals are "polyphasic" and sleep multiple times per 24 hours.

Sleep: Giraffes can go without sleep for weeks, while brown bats sleep for nearly the entire day. Rats have similar sleep needs to humans. Mammals all have the same fundamental sleep cycle. Smaller animals, who often have higher rates of brain metabolism, tend to require more sleep, while larger animals generally get less sleep. All the animals that sleep less than four hours on average are large land ma.