Kratom produces its own withdrawals, in my experience the restless legs/arms is worse than with other opiates. Plus the half-life is so short that it doesn't provide relief for long.
Every time you withdraw from opiates, it gets worse. This is an effect known as kindling, where once you've been dependent on something, it is easier to get dependent again, and the withdrawal gets worse.
Insomnia/restlessness is by far the worst part of opiate withdrawal, in my experience. Benzos can knock you out, but benzo withdrawal is much worse than opiate withdrawal so you have to be really careful.