diff --git a/content/reference.md b/content/reference.md
index 4dfe34e..bdc47c9 100644
--- a/content/reference.md
+++ b/content/reference.md
@@ -7020,7 +7020,7 @@ Return true if the first argument appears as a substring within the second argum
### Types
-#### LISPCONDITION [TYPE]
+#### LISPCONDITION [TYPE]
Condition for lisp error handling. Uses `cl:condition`.
@@ -7038,7 +7038,7 @@ Condition for lisp error handling. Uses `cl:condition`.
### Structs
-#### PROFILE :A [STRUCT]
+#### PROFILE :A [STRUCT]
- OUTPUT :: :A
The output of the function
- RUN-TIME :: COALTON:UFIX
The run time of the run
- REAL-TIME :: COALTON:UFIX
The real time of the run
@@ -7059,7 +7059,7 @@ A profile of a run function.
### Values
-#### (ADD-FEATURE FEAT) [FUNCTION]
+#### (ADD-FEATURE FEAT) [FUNCTION]
(STRING → UNIT)
Adds a feature `feat` to `cl:*features*`.
@@ -7068,7 +7068,7 @@ Adds a feature `feat` to `cl:*features*`.
***
-#### (ARCHITECTURE _) [FUNCTION]
+#### (ARCHITECTURE _) [FUNCTION]
(UNIT → STRING)
The system's architecture (stored at compile time).
@@ -7077,7 +7077,7 @@ The system's architecture (stored at compile time).
***
-#### (ARGV0 _) [FUNCTION]
+#### (ARGV0 _) [FUNCTION]
(UNIT → (OPTIONAL STRING))
The first command line argument (stored at compile time).
@@ -7086,7 +7086,7 @@ The first command line argument (stored at compile time).
***
-#### (CAPTURE-PROFILE F) [FUNCTION]
+#### (CAPTURE-PROFILE F) [FUNCTION]
∀ :A. ((UNIT → :A) → (PROFILE :A))
Runs a function, recording profile information and returning a Profile object.
@@ -7095,7 +7095,7 @@ Runs a function, recording profile information and returning a Profile object.
***
-#### (CMD-ARGS _) [FUNCTION]
+#### (CMD-ARGS _) [FUNCTION]
(UNIT → (LIST STRING))
The current command line arguments (stored at compile time).
@@ -7104,7 +7104,7 @@ The current command line arguments (stored at compile time).
***
-#### (FEATURES _) [FUNCTION]
+#### (FEATURES _) [FUNCTION]
(UNIT → (LIST STRING))
Returns a list of active features, from `cl:*features*`.
@@ -7113,7 +7113,7 @@ Returns a list of active features, from `cl:*features*`.
***
-#### (GC _) [FUNCTION]
+#### (GC _) [FUNCTION]
(UNIT → UNIT)
Perform a full garbage collection.
@@ -7122,7 +7122,7 @@ Perform a full garbage collection.
***
-#### (GET-BYTES-CONSED _) [FUNCTION]
+#### (GET-BYTES-CONSED _) [FUNCTION]
(UNIT → UFIX)
Gets the number of bytes consed (only implemented for SBCL
@@ -7131,7 +7131,7 @@ Gets the number of bytes consed (only implemented for SBCL
***
-#### (GET-REAL-TIME _) [FUNCTION]
+#### (GET-REAL-TIME _) [FUNCTION]
(UNIT → UFIX)
Gets the real-time.
@@ -7140,7 +7140,7 @@ Gets the real-time.
***
-#### (GET-RUN-TIME _) [FUNCTION]
+#### (GET-RUN-TIME _) [FUNCTION]
(UNIT → UFIX)
Gets the run-time.
@@ -7149,7 +7149,7 @@ Gets the run-time.
***
-#### (GETENV VAR) [FUNCTION]
+#### (GETENV VAR) [FUNCTION]
(STRING → (OPTIONAL STRING))
Gets the value of the environmental variable `var`, errors if `var` doesn't exist.
@@ -7158,7 +7158,7 @@ Gets the value of the environmental variable `var`, errors if `var` doesn't exis
***
-#### (HOSTNAME _) [FUNCTION]
+#### (HOSTNAME _) [FUNCTION]
(UNIT → STRING)
Returns the system's hostname. This is a function because the hostname can be redefined.
@@ -7167,7 +7167,7 @@ Returns the system's hostname. This is a function because the hostname can be re
***
-#### (IMPLEMENTATION _) [FUNCTION]
+#### (IMPLEMENTATION _) [FUNCTION]
(UNIT → STRING)
The lisp implementation (stored at compile time).
@@ -7176,7 +7176,7 @@ The lisp implementation (stored at compile time).
***
-#### (LISP-VERSION _) [FUNCTION]
+#### (LISP-VERSION _) [FUNCTION]
(UNIT → STRING)
The lisp implementation version (stored at compile time).
@@ -7185,7 +7185,7 @@ The lisp implementation version (stored at compile time).
***
-#### (OS _) [FUNCTION]
+#### (OS _) [FUNCTION]
(UNIT → STRING)
The system's operating system (stored at compile time).
@@ -7194,7 +7194,7 @@ The system's operating system (stored at compile time).
***
-#### (SETENV! VAR VAL) [FUNCTION]
+#### (SETENV! VAR VAL) [FUNCTION]
(STRING → STRING → UNIT)
Sets an environment variable `var` to string `val`, only if `var` already exists.
@@ -7203,16 +7203,18 @@ Sets an environment variable `var` to string `val`, only if `var` already exists
***
-#### (SLEEP N) [FUNCTION]
-(INTEGER → UNIT)
+#### (SLEEP N) [FUNCTION]
+∀ :A. RATIONAL :A ⇒ (:A → UNIT)
-Sleep for `n` seconds.
+Sleep for `n` seconds, where `n` can be of any type with an instance of `Rational`.
+
+Sleep uses type class `Rational`'s `best-approx` instead of `Real`'s `real-approx` because it handles the approximation without arbitrary precision. The only `Real` type excluded by this decision is `CReal`.
***
-#### (TIME F) [FUNCTION]
+#### (TIME F) [FUNCTION]
∀ :A. ((UNIT → :A) → (TUPLE :A INTEGER))
Run the thunk `f` and return a tuple containing its value along with the run time in microseconds.