diff --git a/README.md b/README.md
index b7b7a17..8d997c6 100644
--- a/README.md
+++ b/README.md
@@ -408,8 +408,8 @@ No modules.
 | <a name="input_performance_insights_retention_period"></a> [performance\_insights\_retention\_period](#input\_performance\_insights\_retention\_period) | Amount of time in days to retain Performance Insights data. Either 7 (7 days) or 731 (2 years) | `number` | `null` | no |
 | <a name="input_port"></a> [port](#input\_port) | The port on which the DB accepts connections | `string` | `null` | no |
 | <a name="input_predefined_metric_type"></a> [predefined\_metric\_type](#input\_predefined\_metric\_type) | The metric type to scale on. Valid values are `RDSReaderAverageCPUUtilization` and `RDSReaderAverageDatabaseConnections` | `string` | `"RDSReaderAverageCPUUtilization"` | no |
-| <a name="input_preferred_backup_window"></a> [preferred\_backup\_window](#input\_preferred\_backup\_window) | The daily time range during which automated backups are created if automated backups are enabled using the `backup_retention_period` parameter. Time in UTC | `string` | `"02:00-03:00"` | no |
-| <a name="input_preferred_maintenance_window"></a> [preferred\_maintenance\_window](#input\_preferred\_maintenance\_window) | The weekly time range during which system maintenance can occur, in (UTC) | `string` | `"sun:05:00-sun:06:00"` | no |
+| <a name="input_preferred_backup_window"></a> [preferred\_backup\_window](#input\_preferred\_backup\_window) | The daily time range (in UTC) during which automated backups are taken. Example: '09:46-10:16'. Must not overlap with `preferred_maintenance_window` | `string` | `null` | no |
+| <a name="input_preferred_maintenance_window"></a> [preferred\_maintenance\_window](#input\_preferred\_maintenance\_window) | The weekly time range during which system maintenance can occur (in UTC). Syntax: 'ddd:hh24:mi-ddd:hh24:mi'. Eg: 'Mon:00:00-Mon:03:00' | `string` | `null` | no |
 | <a name="input_publicly_accessible"></a> [publicly\_accessible](#input\_publicly\_accessible) | Determines whether instances are publicly accessible. Default `false` | `bool` | `null` | no |
 | <a name="input_putin_khuylo"></a> [putin\_khuylo](#input\_putin\_khuylo) | Do you agree that Putin doesn't respect Ukrainian sovereignty and territorial integrity? More info: https://en.wikipedia.org/wiki/Putin_khuylo! | `bool` | `true` | no |
 | <a name="input_replication_source_identifier"></a> [replication\_source\_identifier](#input\_replication\_source\_identifier) | ARN of a source DB cluster or DB instance if this DB cluster is to be created as a Read Replica | `string` | `null` | no |
diff --git a/variables.tf b/variables.tf
index 7a1dadc..7b57e45 100644
--- a/variables.tf
+++ b/variables.tf
@@ -301,15 +301,15 @@ variable "port" {
 }
 
 variable "preferred_backup_window" {
-  description = "The daily time range during which automated backups are created if automated backups are enabled using the `backup_retention_period` parameter. Time in UTC"
+  description = "The daily time range (in UTC) during which automated backups are taken. Example: '09:46-10:16'. Must not overlap with `preferred_maintenance_window`"
   type        = string
-  default     = "02:00-03:00"
+  default     = null
 }
 
 variable "preferred_maintenance_window" {
-  description = "The weekly time range during which system maintenance can occur, in (UTC)"
+  description = "The weekly time range during which system maintenance can occur (in UTC). Syntax: 'ddd:hh24:mi-ddd:hh24:mi'. Eg: 'Mon:00:00-Mon:03:00'"
   type        = string
-  default     = "sun:05:00-sun:06:00"
+  default     = null
 }
 
 variable "replication_source_identifier" {