Stress level in scrum
In the waterfall model, you have periods of high stress before releases followed by low-stress periods. The shortening of this cycle by organizing planning and development into two-week sprints results in shortening the cycle of high and low-stress periods. This raises the overall stress level. Our body is pretty good at handling short periods of high stress, but prolonged periods of high stress are unhealthy.
Source: Why Scrum is Stressing You Out
The structure of a sprint is highly specific to the framework and leaves not much room for the autonomy of the developers. But autonomy is one of the major psychological needs and is important for the motivation and drive of developers. Also, sprints do not leave room for engineering tasks other than implementation, like brainstorming, finding new technical solutions, or learning new patterns.