diff --git a/internal/help/help.go b/internal/help/help.go
new file mode 100644
index 0000000..fb6d7f1
--- /dev/null
+++ b/internal/help/help.go
@@ -0,0 +1,68 @@
+package help
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"github.com/spf13/pflag"
+)
+
+func SetupCustomHelp() {
+	fs := pflag.CommandLine
+	fs.SortFlags = false
+
+	pflag.Usage = func() {
+		name := filepath.Base(os.Args[0])
+		out := fs.Output()
+		if out == nil {
+			out = os.Stderr
+		}
+
+		if err := writeHelp(out, name); err != nil {
+			_, _ = fmt.Fprintf(os.Stderr, "failed to write help output: %v\n", err)
+		}
+	}
+}
+
+func writeHelp(w io.Writer, name string) error {
+	var b bytes.Buffer
+
+	fmt.Fprintf(&b, "%s — sleep cycle calculator\n\n", name)
+	b.WriteString("Usage:\n")
+	fmt.Fprintf(&b, "  %s [mode] [options]\n\n", name)
+
+	b.WriteString("Choose exactly one mode:\n")
+	b.WriteString("  -n, --now                    Calculate wake times from the current time\n")
+	b.WriteString("  -w, --wake HH:MM             Calculate bedtimes for a target wake time\n")
+	b.WriteString("  -s, --sleep HH:MM            Calculate wake times for a target sleep time\n")
+	b.WriteString("  -f, --from HH:MM             Start of sleep window. Use together with --to\n")
+	b.WriteString("  -t, --to HH:MM               End of sleep window. Use together with --from\n\n")
+
+	b.WriteString("Options:\n")
+	b.WriteString("  -b, --buffer int             Minutes to fall asleep (default: 15)\n")
+	b.WriteString("  -m, --cycles-min int         Minimum cycles to show (default: 4)\n")
+	b.WriteString("  -x, --cycles-max int         Maximum cycles to show (default: 6)\n\n")
+
+	b.WriteString("Other:\n")
+	b.WriteString("  -g, --good-night             Print random good night art\n")
+	b.WriteString("  -v, --version                Print version\n")
+	b.WriteString("  -h, --help                   Show help\n\n")
+
+	b.WriteString("Examples:\n")
+	fmt.Fprintf(&b, "  %s --now\n", name)
+	fmt.Fprintf(&b, "  %s --wake 07:00\n", name)
+	fmt.Fprintf(&b, "  %s --sleep 22:30\n", name)
+	fmt.Fprintf(&b, "  %s --from 22:00 --to 07:00\n", name)
+	fmt.Fprintf(&b, "  %s --wake 07:00 --buffer 20 --cycles-min 5 --cycles-max 6\n\n", name)
+
+	b.WriteString("Notes:\n")
+	b.WriteString("  - Time format is 24-hour HH:MM\n")
+	b.WriteString("  - Short hours like 7:00 are accepted\n")
+	b.WriteString("  - Modes cannot be combined\n")
+
+	_, err := io.WriteString(w, b.String())
+	return err
+}
diff --git a/main.go b/main.go
index ee4a5a2..5a6e572 100644
--- a/main.go
+++ b/main.go
@@ -5,12 +5,15 @@ import (
 	"os"
 
 	"github.com/TyostoKarry/sleepycli/internal/goodnight"
+	"github.com/TyostoKarry/sleepycli/internal/help"
 	"github.com/spf13/pflag"
 )
 
 const version = "0.1.0"
 
 func main() {
+	help.SetupCustomHelp()
+
 	var (
 		nowFlag       bool
 		wakeFlag      string
@@ -32,7 +35,7 @@ func main() {
 	pflag.IntVarP(&bufferFlag, "buffer", "b", 15, "Fall asleep buffer in minutes")
 	pflag.IntVarP(&cyclesMinFlag, "cycles-min", "m", 4, "Minimum cycles to show")
 	pflag.IntVarP(&cyclesMaxFlag, "cycles-max", "x", 6, "Maximum cycles to show")
-	pflag.BoolVarP(&goodNightFlag, "good-night", "", false, "Display a random good night art")
+	pflag.BoolVarP(&goodNightFlag, "good-night", "g", false, "Display a random good night art")
 	pflag.BoolVarP(&versionFlag, "version", "v", false, "Print version")
 
 	pflag.Parse()
@@ -49,6 +52,7 @@ func main() {
 
 	if err := validateAndSelectMode(nowFlag, wakeFlag, sleepFlag, fromFlag, toFlag, bufferFlag, cyclesMinFlag, cyclesMaxFlag); err != nil {
 		fmt.Fprintln(os.Stderr, "Error:", err)
+		fmt.Fprintln(os.Stderr, "Run 'sleepycli --help' for usage.")
 		os.Exit(1)
 	}
 }