# Deprecated preventSleep

> **WARNING:** `preventSleep` and `setPreventSleep` were deprecated in 3.0 and will be removed in a future version. They are no-ops: `setPreventSleep` does nothing and `preventSleep` always returns `false`.

## What is deprecated

- `c.setPreventSleep(enabled)` and `c.preventSleep` in TypeScript.
- `Ctx::set_prevent_sleep` and `Ctx::prevent_sleep` in Rust.

examples/docs/actors-deprecated-prevent-sleep/before.ts:

```ts
import { actor } from "rivetkit";

// An actor that still uses the deprecated `setPreventSleep`
const uploader = actor({
  actions: {
    upload: async (c, url: string) => {
      c.setPreventSleep(true);
      try {
        await fetch(url, { method: "POST" });
      } finally {
        c.setPreventSleep(false);
      }
    },
  },
});
```

Because these calls no longer do anything, an actor that relies on them can sleep in the middle of the work they were meant to protect.

## Use `keepAwake` or `waitUntil`

Scope the work that must finish to a promise instead of toggling a flag:

- **`c.keepAwake(promise)`** blocks sleep until the promise settles and returns its result. Use it when the caller waits for the work.
- **`c.waitUntil(promise)`** lets the current request return right away and finishes the promise before the actor sleeps. Use it for background work.

examples/docs/actors-deprecated-prevent-sleep/keep-awake.ts:

```ts
import { actor } from "rivetkit";

const uploader = actor({
  actions: {
    // `keepAwake` blocks sleep until the promise settles and returns its result
    upload: async (c, url: string) => {
      const response = await c.keepAwake(fetch(url, { method: "POST" }));
      return response.status;
    },

    // `waitUntil` lets the action return now and finishes the work in the
    // background before the actor sleeps
    uploadInBackground: (c, url: string) => {
      c.waitUntil(fetch(url, { method: "POST" }));
    },
  },
});
```

In Rust, use `Ctx::keep_awake` and `Ctx::wait_until`. See [Lifecycle](/actors/docs/lifecycle) for how sleep works.