Yes, but not as much as most people think. When we sweat our body is pushing out waste, but part of that is salt. Salt is generally beneficial for locking up hair (with the exception of the twisting method). Therefore sweat isn’t the enemy of your dreads. The true enemy is sebum, which is a waxy oily substance that forms from the accumulation of dead skin cells and natural oils from your scalp. If you aren’t washing frequently enough or with an effective shampoo you will most likely deal with too much sebum leading to dandruff issues or waxy oily scalp which is not good for dreadlocks.